There’s something sinister under the surface of the idyllic, suburban town of Wesley Falls, and it’s not just the abandoned coal mine that lies beneath it. The summer of 1995 kicks off with a party in the mine where six high school students witness a horrifying crime that changes the course of their lives. When they realize that they can’t trust anyone but each other, they begin to investigate what happened on their own. As tensions escalate in town to a breaking point, the six make a vow of silence, bury all their evidence, and promise to never contact each other again. But 20 years later, Jia calls them all back to Wesley Falls. Maddy has been murdered, and they are the only ones who can uncover why. But to end things, they have to return to the mine one last time.

Chloe Sevre is a freshman honor student, a legging-wearing hot girl next door who also happens to be a psychopath. She spends her time on yogalates, at frat parties and plotting to kill Will Bachman, a childhood friend who grievously wronged her. Chloe is one of seven students at her DC-based college who are part of an unusual clinical study of psychopaths --- students like herself who lack empathy and can’t comprehend emotions like fear or guilt. The study, led by a renowned psychologist, requires them to wear smart watches that track their moods and movements. When one of the students in the study is found murdered in the psychology building, a dangerous game of cat and mouse begins, and Chloe goes from hunter to prey.