We see Jake as a young child. His dad tells him goodbye and then goes into the kitchen and shoots himself, right next to where his wife overdosed.
Tommy and Connor find Tessa's dead body in Lindy's apartment with Sophia's cell phone jammed into her skull. The phone warns them that both Lindy and Sophia will die if they follow or call the police. That means it's up to the two guys and George to save them.
Lindy starts connecting the dots and realizes that Jake is Flirtual. She confronts him and he freaks out, knocking her unconscious. She comes to in Mercy Shore's Women's Recovery Center on the island. It's the place where Jake's parents met. Dad was a criminal grave digger, mom was a druggie.
Jake wants Lindy to understand his story, their story. Just because dad couldn't find a perfect woman, doesn't mean he can't. Jake believes that Lindy is his perfect one and therefore he's willing to do anything for her, even kill.
He understands better than anyone how scars from your past can haunt you and he knows that Sara is Lindy's greatest wound. He symbolically recreates the night her little sister was kidnapped, but puts Sophia's life in danger. Then he gives Lindy the opportunity to save her and run, which she does.
The boys work their behind-the-scenes magic and figure out where the girls are. They get there just after Jake stabs Sophia. Lindy forces Tommy to save her friend over her.
Twelve hours later we see Jake and Lindy in a train station. He intends to visit her hometown to look for Sara, but Lindy steals his tablet with all the information about her sister, exposes Jake as the killer with George's help and has him arrested by Tommy.
On her way out of town, Lindy stops by the hospital to make sure Sophia is okay and has a goodbye cyber chat with Tommy. On the bus for home, she watches a video that exposes her sister's kidnapping as a fake. Sara staged her disappearance to keep Lindy safe.