While at a girls' empowerment camp, high school pariah Neve and her new best friend Diane joke about killing each other's bullies, and soon after returning home, Neve finds herself being blackmailed into committing murder.

Neve Lanier was betrayed by her best friend, Yasmin, at the end of the school year. That summer at a girl's empowerment camp she grabs the attention of the charismatic Diane, and jokingly promises to murder Diane's predatory step-brother, Javier, in exchange for Diane murdering Yasmin. But that was just a joke... right? Wrong. When Yasmin turns up dead, Diane comes calling, attempting to blackmail Neve into murdering Javier. As Neve gets to know Javier– and falls for him– she realizes that everything Diane told her is a lie. Yasmin probably wasn't Diane's first victim-- and unless Neve can stop her, she won't be the last. -- adapted from Goodreads info