Oskar looks at the tester page and notices that “Thomas Schell,” his dad’s name, is written there. He asks the manager how often the pages get changed, and she says they would have been changed more recently than a year ago. 

Oskar researches the number of people with the last name “Black” in New York. He calculates that it would take him less than three years to visit all of them if he spent every Saturday and Sunday doing so. 

He decides not to tell his mom about the key because he’s mad at her for spending time with Ron. Every time Oskar leaves during the eight months he spends looking for the lock, he tells his mom he’s going out and will be back later. He believes her lack of follow-up questions means she’s forgetting him. Pursuing the lock makes him feel closer to his dad and farther from his mom. 

On the day his dad died, Oskar replaced their phone with an identical one he buys to protect his mom from hearing the messages his dad left. He keeps the old phone hidden away in his closet. 

Oskar listens to one of the messages his dad left. After, Oskar has to invent and give himself a bruise to cope. He uses his walkie talkie to talk to his grandma. She says she had been talking to the renter. Oskar isn’t sure the renter exists. 

An ambulance goes down the street, and Oskar imagines a device that would let ambulances tell people whether they know the person in it. People could rank everyone they love, so if the person they loved the most was dying, the ambulance could flash, “Goodbye! I love you!” as it passed.