The book begins with several students going about their day at high school. Patrick the detective is in his squad car when the call comes over the radio that there were shots fired at the high school. He arrives at the school and goes in after the shooter against the chief’s orders. He finds his way to the locker room where Peter is sitting in one corner with a gun in his hand. He was unable to commit suicide because the gun jammed. Patrick gets Peter to give up his gun and takes him into custody. Patrick then searches the locker room and finds a boy and girl lying on the floor. The boy, Matt, is dead but the girl, Josie, is alive. Patrick picks her up can carries her out.
The rest of the book bounces between flashback and the present. I will try to lay this out in chronological order.
Lacy (Peter’s mother) is a midwife and assists Alex (Josie’s mother) deliver her baby girl.
Peter and Josie are very close friends as small children and really best friends.
Peter is excited to go to kindergarten but from his first day he gets picked on by just about everyone he encounters including his older brother.
Josie is Peter’s only real friend through grade school.
One day Alex catches Peter showing and handling his father’s guns with Josie. Alex flips out and this causes a rift between the parents. Their children are not allowed to play together anymore but they are still friends at grade school.
In sixth grade, Peter makes fun of a girl who gets her period in class. The next day, everyone plays a joke on the girl but Peter decided that the joke is to mean and does not participate. Josie does however and from that day Josie starts hanging out with the popular kids and shuns Peter socially.
Peter grown increasingly rejected by his peers and feels more and more isolated. His only friends are Derek, a boy he befriends while riding the bench in soccer and the internet. Peter gets deeply involved in games and starts creating his own computer games.
Lacy still works as a midwife. Alex is now the district court superior judge. Josie starts dating the hockey stud and Peter’s main antagonist. Peter learns how to shoot guns and goes hunting with his father for the first time. Alex and Josie don’t really have much of a mother daughter relationship.
The other bullies repeatedly call Peter “homo” and he begins to question his sexuality. Peter goes to a gay bar to test it out. He starts playing pool with an older guy. One of Peter’s teacher’s sees him and escorts him out of the bar and gives him a ride home. From this we learn that Peter is not gay but the teacher is. This teacher is later shot by Peter during his rampage.
Peter’s older brother is killed in his senior year just before graduation. His parents are devastated and their grief causes them to further ignore Peter making him feel more alone and unloved. Peter creates a video game about going through a high school on a shooting spree.
One night Josie and her boyfriend, Matt (a popular hockey player), have unprotected sex and Josie gets pregnant. Not wanting to have an abortion, because that would mean telling her mother, she looks for remedies on the internet to cause herself to miscarry. She finally does and tells her Matt that she is OK now. He is very relieved. Matt is also a very possessive and somewhat abusive boyfriend.
Peter decides to let Josie know about his feelings for her but he does not have the courage to tell her face to face. He sends her a poetic e-mail spilling out how he feels for her. Josie’s friend, Courtney (one of the popular crew) sees this e-mail before Josie does and forwards it to Drew (a fellow popular jock on the hockey team). Drew spams this out to the entire school e-mail network. To make matters worse, Courtney tells Peter that Josie does in fact like him and wants to talk to him. That day at lunch Peter asks Josie to have lunch with him. Josie rejects him and the jocks pull down his pants and expose him to the entire cafeteria and Josie. Peter is mortified by this and this turns out to be the final straw.
Peter goes on his shooting rampage at the school. He targets the popular/beautiful people who mocked him all the time including Drew and Courtney. He kills ten and wounds nineteen. Josie cannot remember what happened in the locker room. Peter’s parents get Jordan (a local hotshot attorney) to represent Peter. It turns out Peter had a hit list of sorts. Pictures that were “X’d” out in a year book were targeted. Josie’s name was crossed out but also circled with the words “let live”.
Alex wants to be a good mother and comfort and talk to her daughter about what happened but since she knows that the case will be tried in her court, she remains emotionally distant. She eventually steps down from the case when the defense lists Josie as a possible witness for the defense. This allows Alex and Josie to start over and have a real relationship. Josie signs a legal affidavit that she doesn’t remember anything so she won’t have to testify.
Alex and Patrick (the detective) start dating after her step down.
The trial begins five months after the shooting and Jordan decides that the best defense is to try the “battered woman” defense with Peter. He was bullied so much his only recourse to defend himself was to do what he did and claim he was suffering from post traumatic stress syndrome. They show a surveillance video of Peter entering the cafeteria shooting people. Peter stops during the rampage and calmly eats a bowl of cereal before reloading and leaving the lunchroom to continue his rampage.
Lacy is called to testify on Peter’s behalf and it goes reasonably well until someone in the crowd loses it and starts screaming at her. After this, Peter decides that he needs to tell his story and let people know why he did it. Jordan is against the idea but Peter is insistent. Peter now knows that he will not get off and he will spend the rest of his life in prison.
Peter’s testimony goes OK. He talks about being bullied and starts sounding sympathetic. But then he says that in the game, he always won when he did the shooting and that the game is not over yet. Jordan knows this is a disaster but thinks he can fix it in redirect. The prosecution does not ask any questions and Peter and Jordan are sunk.
Out of desperation, Jordan decides to call Josie to testify in the hopes of saving the case. Josie is very upset and Alex is furious. They all meet in Jordan’s office when Josie sees something that causes her to have a breakthrough. She has been remembering things little by little. She says that Peter’s backpack fell and Matt grabbed the second gun and fired at Peter before Peter fired at Matt. The gun jammed and Peter shot Matt. Alex knows that she will have to perjure herself when she testifies against her affidavit. Alex tells Patrick about this and he goes back to the high school to try to find that bullet that Matt fired.
Josie is called to the stand and she begins to recount the events. When Peter came into the locker room her aimed the gun at Matt. Josie screamed and Peter’s backpack fell off and the second gun slid next to Josie. She grabbed the gun and pointed it at Peter. Peter still aimed at Matt. Matt screamed at her to shoot. Peter pleaded with her to let him finish this. Matt was screaming at Josie to shoot and she did. She shot Matt in the stomach. Peter then came over and shot Matt in the head. Peter tells Josie not to say anything. He still loves her enough to take the fall for her. Then Josie fainted and falls where Patrick found her in the beginning of the book.
The courtroom goes bananas. The judge calls fifteen minute recess. Patrick goes to the prosecutor and presents evidence that he gathered overnight that Matt was not shot by Peter. She tells him that Josie just confessed.
Peter is convicted of eight counts of first degree murder and 2 counts of second degree murder. He later commits suicide after a few months in jail by stuffing a sock down his throat and suffocating. Josie was charged as an accessory to second degree murder and sentenced to five years. Alex resigns her appointment to the district bench and goes back to being a public defender. Alex is pregnant with Patrick’s baby.