Percy Jackson, the main character, is a 12-year-old boy and recent student at Yancy Academy, a private school for troubled kids. His life changes dramatically after a school field trip to the Metropolitan Museum of Art. Here, students admire ancient Greek and Roman art and share knowledge on the Greek gods. Previous field trips did not bode well for Percy after mysterious accidents occurred. On this trip, two chaperones lead the group of tweens: Mr. Brunner, the Latin teacher and Percy’s favorite, and Mrs. Dodds, the math teacher. Percy’s only friend, Grover, is on the trip as well. As the group explores the museum, Mr. Brunner approaches Percy and tells him that he holds great promise, leaving Percy perplexed with his below average grades and dyslexia.
After an altercation with bully Nancy Bobofit at the water fountain, Percy is falsely accused of pushing her. Mrs. Dodds leads Percy deeper into the museum to punish him. As she is demanding a confession from Percy, she transforms into a Fury, a mythical creature with bat wings and yellow fangs. Mr. Brunner appears and tosses Percy a ballpoint pen that turns into a bronze sword. Percy swings the sword, striking the monster, and it turns to dust. Dazed by this experience, Percy returns back to the fountain only to discover that, in everyone else’s minds, Mrs. Dodds never existed. Grover tells him that Mrs. Kerr has always been their math teacher, leaving Percy more confused than ever.
No one seems to recall Mrs. Dodds’ existence, after Percy destroyed her, so he is even more convinced something strange is going on. Frustrated by this and other strange occurrences, his grades drop, he fights with Nancy, and then disrespects a teacher. With the end of the school year approaching, Percy is expelled from returning to Yancy Academy in the fall, but he is allowed to finish out the school year. Percy decides the only final he will prepare for is Latin since Mr. Brunner is his favorite teacher. He approaches Mr. Brunner’s office and overhears a conversation between Mr. Brunner and Grover regarding the incident with Mrs. Dodds. They talk about magical mist making the students and staff forget the altercation. Then Grover says that Percy may be the only one who can save them from the “Kindly Ones” before the summer solstice.
After the school year ends, Percy confronts Grover about his conversation with Mr. Brunner while riding on a bus. Grover confesses to being Percy’s protector before the bus breaks down. Off the bus, across the street, Grover and Percy see three old women knitting. Grover seems to be worried and makes Percy promise him that they will walk to Percy’s home together. Percy agrees and watches as the woman in the middle cuts a string. Back on the bus, Grover and Percy discuss the implication of what they saw. The cut signifies someone is going to die.
After arriving at the bus terminal, Percy ditches Grover and departs for home on his own. Before entering the apartment, he tells readers about his mother, Sally Jackson. She is the best person Percy knows, despite some unfortunate circumstances in her life. Percy’s father was the only great break she received although they never married, and Percy has no memories of him before he left for an ocean voyage. Sally later married Gabe, whom Percy refers to as “Smelly Gabe, the world-class jerk.” Inside the apartment, Smelly Gabe rudely welcomes Percy home and Percy storms upstairs to his bedroom. He is later comforted by his mother who gives him the exciting news about taking a trip to Montauk Beach where she met his father. As they are leaving for their trip, Smelly Gabe warns Percy not to damage his car.
While at the beach, Sally answers some of Percy’s questions about his father. He learns that his father wanted to send him to a special camp, but Sally couldn’t bring herself to take him there. That night, a knock on the door amidst the hurricane brewing outside wakes Percy and Sally. Sally opens the door to Grover who says he has been searching all night for Percy since losing him at the bus terminal. Sally is not fazed by Grover’s presence other than why he came and demands that Percy tell her everything that happened at Yancy and at the museum. After Percy finishes telling his mother everything, the three of them run to the car where Percy notices Grover has hooves for feet.
While driving away from the storm, Percy notices a creature following them in the distance. He questions Grover and Sally’s relationship and what kind of animal Grover is. Grover explains that he is a satyr in charge of protecting Percy, but the less he knows, the fewer monsters he will attract. Sally begins driving Percy to the camp for protection after learning that the three old women Percy encountered were the Fates. The car swerves into a ditch, which injures Grover. Sally encourages Percy to get help by running past a big tree that marks the property line to safety. He refuses to leave without her and Grover, despite the creature that is steadily creeping up on them.
Sally and Percy finally pull Grover out of the car and head toward the tree. Outside of the car, Percy recognizes the monster as half bull, half man. He starts to name the monster, but his mother warns him that names have power. She advises him to jump to the side if the creature attacks, since a bull cannot change directions easily. Percy does so when the bull charges, which angers the monster. The monster then attacks his mother and Grover who are on the side of the road. The bull-man grabs Percy’s mother by the neck, and she disappears into a golden light. Furious, Percy defeats the monster by tearing off one of the monster’s horns and shoving it into the monster’s ribs. Percy helps Grover to safety and the two pass out on the porch of a farmhouse after a young girl recognizes him as the “one.”
After being nursed back to health, Percy enjoys the beautiful views of the camp, despite feeling remorse for what he assumes was his mother’s death. He tries to remember the battle with the bull-man, which he now calls the Minotaur. Grover apologizes to Percy for not being able to save Sally and for his failure in the role of a keeper. Percy does not blame Grover though and the two leave the farmhouse and enter into the main part of Camp Half-Blood. Percy meets Mr. D, the camp director; Chiron, who he knew as Mr. Brunner; and Annabeth, one of the daughters of Athena. He learns that Chiron had been at the school to teach Percy after Grover suggested that Percy was special.
Percy joins Chiron, Mr. D, and Grover in a game of pinochle. While playing the game, they discuss the presence of Greek gods in the world and comment on how Mr. D is one himself: Dionysus, the god of wine. Mr. D and Grover leave so that Chiron and Percy can have a private conversation. Chiron and Percy discuss more about Mount Olympus and the Greek gods. Chiron tells Percy that he will learn more about himself and his role after he gets settled in his cabin. At this point, Percy sees Chiron as his true self—a centaur.
While walking Percy to his cabin, Chiron gives Percy a tour of the camp. Percy learns this was Grover’s second chance to restore his role as a keeper after he failed five years ago. Percy fears he will be in trouble if Mr. D and the Council of Cloven Elders consider his mission to protect Percy a failure. Upon approaching the cabins, Percy notices that each cabin features a mascot dedicated to a god. Annabeth greets him before he enters his cabin. He has been placed in “Hermes,” the cabin for undetermined campers. Here, he meets his cabin counselor, Luke, the son of Hermes.
Percy is disappointed that he has not received proper recognition for fighting the Minotaur and leaves the cabin. Annabeth joins him outside and explains that monsters do not die because they lack a soul. They can still reform and he should refer to them as “Kindly Ones,” rather than by their names. Annabeth also points out that Percy would not be here if he were not a half-blood by his father. As they are talking, another girl, Clarisse, the daughter of Ares, provokes Percy and Annabeth into a fight in the bathroom. Percy defends himself by unknowingly manipulating the water to soak Clarisse and her friends. Angered and humiliated, she declares war on Percy.
Percy feels overwhelmed by his new home and everything he is learning as he continues to wonder who his father is. Annabeth tells him that although he may never know, it is important that he remain at the camp in order to protect himself from monsters and mortals. The camp’s border does not allow monsters or mortals to enter unless summoned by someone within the camp. If he were to stay in the mortal world, he would be more susceptible to danger. Annabeth explains that Percy is only allowed to leave the camp with permission or if assigned to a quest.
Percy asks Annabeth what she knows about the summer solstice. She only recalls an unease with the weather after her trip to Mount Olympus for the winter solstice with Clarisse and Luke. She also overheard talk about something that was stolen and if the item was not returned by the summer solstice, a war would break out. Percy and Annabeth return to their cabins where Percy chats with Luke. Luke tells Percy that although Annabeth desperately wants to go on a quest, she is unable to until somebody special arrives. Percy does not understand what Luke means but drops the conversation.
As Percy settles into the camp, he discovers his skill in sword fighting, his gift with water, and his father’s identity. During a sword-fighting lesson with Luke, Percy successfully beats him, which catches Luke off guard. Later, Percy asks Grover about Grover’s desire for a searcher’s license. Grover does not share much detail other than how he may be one step closer if he successfully protects Percy during a quest. They also talk about the “Big Three” gods: Zeus, Poseidon, and Hades.
Grover explains that the children of the “Big Three” gods are more powerful than other half-bloods. Because of this, the “Big Three” decided not to have any more children after they recognized that their children were causing catastrophic events. Zeus, however, broke this pact by having a daughter named Thalia. Hades was angered at Zeus for his indiscretion and sent monsters to attack Thalia. She sacrificed herself by fighting the monsters alone to save other half-bloods and a satyr who were accompanying her on their way to Camp Half-Blood. As Thalia was dying, Zeus turned her into a pine tree. Through this tree, now called Half-Blood Hill for her heroic act, Thalia’s spirit still protects the surrounding borders.
In the evening, during a game of capture the flag, Percy is attacked by Clarisse and several other campers, leaving a deep wound in his arm. Percy falls back into a creek and, even though he is weak, he is mysteriously able to defend himself against his opponents. Meanwhile, Luke wins the game for his cabin. Annabeth magically appears near Percy in the creek after taking off her invisibility cap. As they are getting out of the water, Annabeth notices that Percy’s arm has already healed. Suddenly, a hellhound from the Fields of Punishment attacks Percy, but is promptly killed by arrows fired by Chiron, piercing its neck. Chiron trots over and points out that someone from inside the camp must have summoned a monster to attack Percy. As Percy resubmerges into the water to heal, a hologram of green light shines above him and reveals that Poseidon has claimed Percy as his son.
The camp responds to Poseidon’s claim by granting Percy his own private cabin as well as other freedoms, while also assigning him to a world-saving quest. Despite these luxuries of freedom, Percy feels isolated and angered after hearing he is being blamed for his mother’s disappearance back home. That night, Grover encourages Percy to talk with Chiron about accepting the quest and speaking with the Oracle about his destiny. Percy agrees to the quest and Chiron explains why Zeus and Poseidon are fighting. Zeus believes that Poseidon stole his lightning bolt, the symbol of his power. Poseidon denies this allegation and seeks an apology by the summer solstice, the day Zeus also wants his master bolt returned by. If the quest fails, a catastrophic war will be unleashed. Zeus thinks that having Poseidon’s son return his bolt will be a rewarding peace offering. Percy seeks advice from the Oracle and learns that he has to go west and face a god to find the stolen item. The Oracle tells him that along the way, he will be betrayed by a friend and fail to save what matters most.
Chiron tells Percy that he suspects that Hades stole the master bolt because he was angry that Zeus broke their pact by having another child. He knew that Zeus would blame Poseidon and a war would unfold. Chiron believes Hades also knew Poseidon would claim Percy as his son, so Hades has tried to kill Percy by sending monsters such as the Minotaur before Percy’s quest could begin. Percy is angry that Hades’ desire to kill him caused his mother to disappear and has instilled fear in the rest of the camp. He takes Grover and Annabeth on the journey, so that Grover can get his searcher’s license and Annabeth can fulfill her desire for a quest.
As Percy, Grover, and Annabeth prepare to depart for their quest, Luke gives Percy magical shoes that fly. As a precaution, Percy hands the shoes over to Grover because Percy fears that Zeus will strike him down if he travels through the sky. Chiron gives Percy the ballpoint pen that transforms into a sword, named Riptide. The sword cannot be lost. It cannot hurt any mortal, only monsters, but Percy is reminded that he is susceptible to both mortal and celestial weapons.
Once in the city, Percy starts thinking about his family. Grover shares with Percy how his mother was protecting him by staying with Smelly Gabe because his scent masked Percy’s scent from monsters. While they are on a bus headed toward the entrance to the Underworld, three old women who look like Mrs. Dodds get on the bus. These women are actually monsters. They are called the Furies. Percy wears Annabeth’s invisible cap and slips past them, hoping that the Furies only want him and will ignore his friends. Instead, the Furies attack Annabeth and Grover.
While still invisible, Percy spins the bus by taking control of the steering wheel. He pulls the emergency brake and releases the mortals from the bus. Then he takes off the cap and instigates a fight with the monsters, so they will leave his friends alone. Annabeth and Grover help hold the Furies while Percy uses Riptide to turn the first two to dust. As Percy strikes the third Fury, he and his friends escape from the bus just as it bursts into flames. The Mrs. Dodds look-alike calls for reinforcements amidst the flames and the three friends flee into the nearby woods.
Percy, Annabeth, and Grover emerge from the woods and come upon a curio shop that smells like food. As they stop to eat, Grover notices a life-size statue outside that looks strangely like his Uncle Ferdinand. A woman who calls herself Aunty Em feeds them and offers to take their picture. Percy accepts the offer, but Annabeth and Grover are skeptical about the woman’s statues. Suddenly, Grover realizes that the statue was his uncle and Annabeth warns Percy and Grover to look away from the woman. Percy learns that Aunty Em is actually Medusa, a monster seeking revenge on Annabeth for being the daughter of Athena, the god who cursed her. She tells Percy that he would be better off as a statue than having to play the Olympians’ game.
Grover attacks Medusa with a tree branch with his eyes shut while Percy uses the reflection of a gazing ball to approach her. Percy severs Medusa’s head with Riptide. Annabeth says that even though the head is a spoil of war it can still turn him to stone. Tired of being used as a pawn, Percy steals money from Medusa’s office to use on their journey. He grabs a freight bill showing the Underworld’s billing address and now knows it is located at a DOA Recording Studio in California He finds a box and fills out a delivery slip to send Medusa’s head to Mount Olympus before they plan their next move.
Back in the woods, Percy, Annabeth, and Grover rest for the night while Percy learns that in order to earn his searcher’s license, Grover must find Pan, the god of wild places. To the satyrs, Pan is their master who once protected the earth. Although legend says that he died, the satyrs refuse to believe he is gone and many dedicate their lives to finding him, although none have survived the search. Grover says that despite the risk, he still desperately wants to search for Pan to restore the earth’s goodness.
On this part of the trip, Percy also discovers that Grover was the keeper for Annabeth five years ago when he failed, but she forgave him. Grover stops Percy from asking more questions about that quest and instead says how he and Annabeth think this quest is different because the monsters seem to be holding back from attacking them while they look for something. The next morning, Percy meets Gladiola, a missing pink poodle. They collect enough money to buy train tickets by returning Gladiola to his owner.
The Amtrak train takes Percy, Annabeth, and Grover to Denver. Percy tries to keep a low-profile after his image is plastered on the front page of newspapers as a wanted fugitive for the disappearance of his mother and for the flaming bus accident. While Percy takes a nap, he dreams of a dreary, scary pit and tries to barter to save his mother’s life. Later, Annabeth reveals that she ran away to Camp Half-Blood when she was seven after learning that her father never wanted her and resented her after he remarried.
The three explore the top of the Gateway Arch during a layover in St. Louis. Percy waits at the top of the Arch with the other tourists while Annabeth and Grover take the remaining seats on the elevator back down. A fat woman and a Chihuahua confront Percy and reveal that they are monsters trying to hurt him. The woman is the Mother of Monsters, a reptile-looking creature named Echidna. The Chihuahua is actually Chimera, a rabid, fire-breathing, lion serpent. Chimera attacks Percy by plunging its serpent fangs into Percy’s leg and damaging the Arch with a ball of fire. Percy feels defeated after he loses Riptide trying to defend himself and the other tourists. Echidna taunts him, saying if he truly believed he were the son of Poseidon then he would jump into the water to save himself. Percy prays and jumps into the river.
As Percy enters the water, he realizes he wasn’t hurt by the impact of the water or Chimera’s bite, but rather feels dry and can breathe underwater. As he looks around, he sees Riptide a few feet in front of him. A female spirit tells him that his father believes in him, he should go to Santa Monica before going to the Underworld, and to not trust gifts. Before she departs, the spirit reassures Percy that his mother’s fate is not hopeless. As the spirit disappears, Percy grabs Riptide and swims off to find Annabeth and Grover.
Several news stations and police officers surround the area below the Arch, as they try to figure out what happened to it. Eyewitnesses tell them they saw a boy jump into the water. As ambulance technicians attend to the civilians on the roof, Percy finds his friends and tells them everything that happened. While they make plans to go to Santa Monica, they hear news reporters making the connection between the boy who jumped and the fugitive they have been reporting on. The three quickly dash toward the train station before anyone recognizes Percy and head to Denver.
In Denver, Percy, Annabeth, and Grover contact Chiron through Iris-messaging, the rainbow goddess who carries messages for the gods. Luke answers and is updated on all that has happened so far. Percy and Luke discuss the possibility of Hades stealing the master bolt during the winter solstice by using his Helm of Darkness. While eating at a diner, Ares, Clarisse’s dad and the god of war, joins the group and asks Percy to retrieve his shield, which he lost in the Tunnel of Love while at a waterpark with his girlfriend. In turn, Ares will disclose information about Percy’s mother and help the three continue west.
After initial reluctance, Percy and his friends head to the waterpark. Percy discovers that Ares was dating Aphrodite, the goddess of love, despite Aphrodite’s marriage to Hephaestus, the blacksmith. Hephaestus is aware of his wife’s affair and always tries to embarrass her and Ares. While Grover stands guard, Percy and Annabeth are caught in a trap that was set by Hephaestus to catch his wife and Ares together. A camera emerges and spotlights shine down on Percy and Annabeth. A loudspeaker voice announces the beginning of a countdown until the broadcast goes live to Mount Olympus. Annabeth is concerned about looking like a fool before the gods until thousands of metal spiders emerge and begin to swarm toward them. Annabeth is paralyzed with terror. Percy moves her back to the boat and uses his connection with water to move the boat along and fight off the spiders. Before the boat crashes, the two of them jump and Grover grabs them by flying with his shoes and carries them to safety before dropping them along the way. They survive the fall and Percy vows to confront Ares on this assignment.
At the diner, Percy and his friends return the shield they recovered to Ares. He takes his shield and gives Percy a backpack with food and directs them to a truck that will take them to Los Angeles. Before leaving, Ares tells Percy that his mother is not actually dead, but rather a hostage in metamorphosis. Percy, Annabeth, and Grover join some caged animals on the truck headed to Los Angeles with a stop in Las Vegas. While on the road, Percy learns that Grover was the keeper for Thalia, Zeus’ daughter who died. The two half-bloods she was protecting at the time were Annabeth and Luke. Annabeth shares how she tried to reconcile with her family a couple of years ago only to return to Camp Half-Blood.
Percy dreams about the pit again. He hears a mysterious voice and sees his mother reaching out to him but wakes up to the truckers checking on the animals. After witnessing the abuse of some of the animals, Percy releases them into Vegas while he and his friends leave the truck. They enter the Lotus Hotel and Casino and are given a room key. They shower, eat, relax, and play video games until Percy realizes something seems off. People appear to be in a daze. No one can tell him what year they are in. Percy snaps Annabeth and Grover out of the trance they are in and they leave the hotel only to realize that since they lost track of time, they only have one day left to complete the quest.
While on the taxi ride to Santa Monica, Percy tries to explain his dream of the pit, but Annabeth reassures him that Hades has the master bolt and there is nothing else to fear. At the beach, Percy submerges into the water and is greeted by Nereid, the spirit of the sea. Nereid gives Percy three pearls and tells him to trust his heart on when to use them. She reminds him that if something belongs to the sea, it will eventually return. Percy meets with Annabeth and Grover on land and they search for the entrance to the Underworld.
Down an alley, a group of boys start a fight, so the three flee into a waterbed store. They are welcomed by a salesclerk who calls himself Crusty. He prompts them to lie down and relax. When Annabeth and Grover take him up on it, ropes suddenly trap them to the beds. Crusty reveals himself to be Procrustes, the Stretcher, and attempts to attack Percy. However, Percy distracts Crusty by pretending he is interested in the waterbed. He persuades Crusty to demonstrate, which allows him the opportunity to trap Crusty with the ropes and use Riptide on him. Percy frees Annabeth and Grover from being stretched. Percy sees a flyer on a bulletin board for the DOA Recording Studio showing the exact address for the Underworld entrance.
Annabeth, Percy, and Grover arrive at the recording studio, and meet a security guard named Charon who asks them to pay for their entrance. Percy gives him some drachmas he stole from Crusty’s office before they left. Charon is not happy with the amount and will not allow them to enter. After Charon recognizes Percy is a godling, Percy hands him a bag full of drachmas and says that he will put in a good word with Hades about giving Charon a proper raise. Charon agrees and the group departs toward one of three entrances with metal detectors and security cameras.
Before passing through the security line, the three are stopped by Cerberus, a three-headed security Rottweiler. Percy tries to distract him with a bedpost he took from Crusty’s, but Cerberus is not interested in “the stick.” Annabeth pulls out a ball she took from the waterpark and commands Cerberus to sit. Percy and Grover are able to sneak past the dog while Annabeth distracts him. She tosses him the ball and catches up with Grover and Percy. They set off the metal detectors with their magical items and run to escape the security guards.
As Percy, Annabeth, and Grover head toward the house of Hades, the flying shoes Grover is wearing take off and fly him toward the pit from Percy’s dream. The shoes fall off of Grover before he falls into the pit as Percy and Annabeth catch up. When they sit down to catch their breath, Percy notices that his backpack feels heavier. A whisper echoes from the pit signifying the entrance to the stormy pit of Tartarus and the three flee before they are sucked down.
Finally, they meet Hades who accuses Percy of stealing not only the master sword, but also his Helm of Darkness. Hades claims he does not want war because he would have to hire more staff to support the extra deaths. Percy denies stealing either item, but Hades warns him that he will unleash the dead back into the world if his helm is not returned. Hades tells Percy to check his backpack. Percy opens it and reveals the master sword in his possession. Percy feels defeated, knowing that someone has been manipulating him. Hades says he knows that Percy came to bargain for his mother’s life. He then shows Percy a vision of his mother in a ball of gold fire.
Hades threatens to kill Percy’s mother if he does not return his helm. Percy grabs the pearls to leave Hades, but realizes he only has three and cannot save himself, his friends, and his mother. He gives up the idea of a joyful reunion with his mother and uses the pearls to escape with Annabeth and Grover in order to return the master bolt to Olympus. The three are dropped into the ocean at Santa Monica and plan to not only return the master’s bolt, but also to talk with the god who tricked them.
On the shore, Percy, Annabeth, and Grover confront Ares about stealing the master bolt and the Helm of Darkness. Ares admits that while he did not personally steal them, since gods cannot steal each other’s symbols of power, he did have someone else take it. Ares wants war, so he framed Percy as the culprit in order to achieve a three-way war against Poseidon, Zeus, and Hades. He explains that magic similar to that in Riptide, the sword, was used on the backpack, so that the bolt would appear in the backpack once Percy entered the Underworld. Since Percy still has the master bolt, Ares says he will have to kill Percy so that it cannot be returned to Zeus.
Percy and Ares make a deal that they will fight and if Percy wins, he will return the bolt and be free from Ares; however, if he loses, Ares can take the bolt and transform Percy into anything Ares wishes. The two engage in battle but are interrupted by mortals who recognize Percy as the boy from the news. Ares fires at the mortals while Percy uses the waves against him and stabs him in the heel. As Ares prepares to implement his next attack, a strange force stops him and he lowers his sword in defeat. He tells Percy to watch out because he’s made a new enemy, then disappears in a bright light.
The Furies appear next and take the Helm of Darkness to return to Hades after they acknowledge that Percy did not steal it. As they fly away, Percy joins Grover and Annabeth and they briefly ponder who or what stopped Ares from continuing the fight. The three decide the fastest way to get to New York to return the bolt is by flying in an airplane, despite Percy’s fear of Zeus’s wrath.
In Manhattan, Percy separates from Annabeth and Grover so he can return the master bolt to Zeus while Annabeth and Grover go back to Camp Half-Blood to tell Chiron everything that has happened. At Olympus, Percy delivers the master bolt to Zeus and Poseidon and discloses details of his quest. He tells them about the fight with Ares as well as the unease he encountered while at the entrance of Tartarus. Zeus dismisses Percy’s concerns and spares his life since he returned the bolt. Poseidon reassures Percy that he claims him as his son and tells Percy that he will have a decision to make regarding a delivered package when he returns home. At this time, Percy also learns that his mother was returned home after Hades received his Helm.
Back home, Percy reunites with his mother and Smelly Gabe. Smelly Gabe blames him for his destroyed car and says he is not welcome there. He raises his hand to hit Sally when she tries to defend Percy. Sally and Percy retreat upstairs to his bedroom where Percy finds the package containing Medusa’s head. He suggests that Sally use the head against Smelly Gabe. Percy decides to leave for Camp Half-Blood and says goodbye to his mother.
Percy returns to Camp Half-Blood and is welcomed with praise and celebratory gifts. In a letter, his mother tells him that Smelly Gabe mysteriously disappeared and she has received a nice commission on her sculpture. She used the money to buy a new apartment, enroll at NYU, and hold a spot at a private school in New York for him. With that information, Percy realizes he has to decide if he wants to stay at Camp Half-Blood year-round or return home during the school year. Later that evening, Grover says goodbye to Annabeth and Percy as he departs on his search for Pan.
To clear his head and decide what to do in the fall, Percy begins sword training. He sees Luke fighting dummies with a new sword named Backbiter, a two-sided sword that can kill mortal and creature. The two boys sit by a tree to talk and Percy gets the impression that Luke is getting ready to say goodbye. Suddenly, Luke snaps his fingers and a scorpion the size of Percy’s hand appears from the pit. Luke points out that these scorpions can jump fifteen feet and the stinger can slice through clothes to kill someone in sixty seconds.
During their conversation, Percy realizes that Luke is the missing piece from his prophesy: the betrayal of a friend. Luke felt deceived by the gods for sending him on a pity quest—one that had already been previously fulfilled by Hercules. He was frustrated with the gods for repeating the same quests when there was so much more out there, so he began to listen to urgings from Kronos and stole the bolt and the helm during the winter solstice. When caught by Ares, Luke convinced him that hiding the items would result in a war between the gods. At this point, Luke admits to summoning the hellhound to attack Percy in order to instill fear in the camp and propel Percy’s quest. He also admits that part of his plan failed when Percy gave the gifted shoes to Grover. The shoes were cursed and were supposed to drag Percy and the bolt into Tartarus.
Luke declares that Kronos will rise and that the Olympians will be overthrown. Then he disappears while Percy tries to fight off the scorpion. Percy slices the scorpion but not before he is stung with poison. Although Percy tries to heal himself with the creek water, he is saved by Chiron’s magical nectar. He then tells Annabeth and Chiron about Luke’s deception and vows to take revenge. However, Chiron redirects Percy by pointing out that he will get his justice when the time is right. Annabeth has reconciled with her family and they arrive to take her home. Percy decides to go home as well and plans to fight Luke next summer.