The two-paragraph version: Erika and her husband Jason is the parents of two teenaged children, Hannah and Liam. One of them, Liam, has had sociopathic tendencies in the past, though only Erika knows about it. When a girl Liam likes from his school, Olivia, goes missing Erika worries that it was him. As the police investigation progresses, Liam is arrested. Erika also learns that her father, who she previously believed died in a car accident when she was a child, is alive, but has been in prison for the past 40 years for murder. She wonders if Liam got it from him.
Eventually, it’s revealed that the abductor is her husband Jason. Unlike Liam, who went to therapy when he started displaying antisocial behaviors, Jason’s parents treated him roughly, and Jason eventually murdered them. Liam and Erika confront Jason, and Liam stabs and kills Jason, though Erika tells the police she did it. Olivia is saved (along with Hannah who had also learned that Jason was the perpetrator. Jason is eventually linked to 12 other murders. Erika apologies to Liam for believing it was him. Still, in the Epilogue, another teenaged girl goes missing nearby and Erika worries if could be Liam.
Erika Cass is the mother of two children, Hannah, 14, and Liam, 16. She’s married to Jason, a wealthy tech founder. Her son Liam is charming and polite, but he has a terrifying dangerous streak beginning from when he was a young child. In grade school, he trapped a female classmate in the janitor’s closet and expressed that he wanted a wife so he could trap her in a hole in the ground. Only Erika and Liam are aware of this.
When Erika learns that Liam is interested in someone named “Olivia” at school, she attempts to contact a private detective, Frank, to tell her to stay away from Liam. Erika believes it’s someone named Olivia Reynolds who is on the debate team with Liam. However, soon, a girl named Olivia Mercer disappears after meeting up with Liam at night.
Erika also learns from her mother that her father, Marvin, who she previously believed died in a car accident when she was a child, is alive, but has been in prison for the past 40 years for murder. He has recently been released on parole. Erika decides to track him down to try to understand him better, in hope of understanding Liam better in case Liam got his dangerous tendencies from him. She asks Frank to track him down. He does, but Erika goes to talk to Marvin, and it seems like the murder was the result of a selfish accident (secretly giving his mistress pills to abort an unwanted baby) as opposed to true psychopathy.
The rumor mill soon identifies Liam as the likely abductor of Olivia Mercer, and the police investigation points to Liam as well. There was an incident with Liam starving pet hamsters when he was a child and the incident with the janitor’s closet caused Erika to send Liam to a child psychologist for two years.
A former English teacher, Richard Young, claims Liam gave his family carbon monoxide poisoning in retaliation for giving him bad grades. And a classmate at school, Tyler, used to be friends with Liam but ended their friendship cause Liam seemed crazy. However, Hannah counters this by saying that Tyler is a terrible human being and a bully. She says that Liam got mad at Tyler for being a jerk to Hannah after she told Tyler to stop being creepy with one of her female friends.
After traces of Olivia’s DNA are found in the trunk of the Cass family car. Liam is arrested, but released on bail.
Meanwhile, Olivia is alive but being slowly starved to death in a pit dug into the ground while being periodically visited by her captor. She tries unsuccesfully to escape. Finally, Hannah Cass shows up, saying she followed “him” there to this cabin — and the book reveals that Olivia’s captor is Jason Cass, Hannah and Liam’s father. Jason shows up soon afterwards.
Unlike Liam, who went to therapy when he started displaying antisocial behaviors, Jason’s parents treated him roughly, and Jason eventually murdered them. Jason is a true psychopath, and he puts Hannah in the pit as well, intending to kill her. Jason was also the one responsible for giving Richard’s family carbon monoxide poisoning, and he was hoping Liam would go to prison for murdering Olivia. Jason has been wanting Liam in jail since he felt that Liam was a liability and didn’t want him going back to therapy and potentially revealing that Jason is where he gets his dangerous tendencies from.
Liam and Erika soon arrive at the cabin as well since Liam knew Hannah was headed there. They confront Jason. Liam ends up stabbing and killing Jason, though Erika tells the police she did it in order to protect Liam. Olivia is saved, along with Hannah. Jason is eventually linked to 12 other murders. Erika apologies to Liam for believing it was him. Still, in the Epilogue, another teenaged girl goes missing nearby and Erika worries if could be Liam.
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