What is the climax of bystander by James preller?

The climax of Bystander by James Preller occurs when the main character, a writer named Mark, confronts the killer, William. Mark has been tracking William, who is a serial killer who has been murdering young women in the city. Mark has discovered that William is a high-profile businessman and family man, and he is shocked to learn the truth about him. Mark breaks into William's house, and the two men face off in a tense and violent confrontation in which William reveals the dark secret that has been driving his actions.