Five years ago, high school senior Helena Kelly disappeared from her backyard in Dexby, Connecticut, never to be heard from again. Her family was left without any answers--without any idea who killed Helena, or why.
So when eighteen-year-old Seneca Frazier sees a desperate post on the Case Not Closed message board, she knows it's time to change that. Helena's high-profile disappearance is the one that originally got Seneca addicted to true crime. It's the reason she's a member of the site in the first place.
Determined to get to the bottom of the mystery, she agrees to spend spring break in Connecticut working on the case with Maddy Wright, her friend from Case Not Closed. However, the moment she steps off the train, things start to go wrong. Maddy's nothing like she expected, and Helena's sister, Aerin, doesn't seem to want any help after all. Plus, Seneca has a secret of her own, one that could derail the investigation if she's not careful.
Alongside Brett, another super-user from the site, they slowly begin to unravel the secrets Helena kept in the weeks before her disappearance. But the killer is watching... and determined to make sure the case stays cold.