When June Lee's older sister Lily is horrifically stabbed to death at a secret party in front of a dozen of Lily's friends, June learns about the secret, exclusive "Murder Club" Lily was in, and the thrilling murder mystery game that club members played on Murder Nights.

The police rule Lily's death an accident and close the case. Aggravatingly, everyone—including Lily's boyfriend and closest friends—seems willing to accept that Lily's death was just a tragic accident…everyone but June. Determined to find out more about the Club, its members, and exactly what happened at that party, she enlists the help of Alex Torres, the only club member who wasn't there that particular Murder Night when Lily died, and therefore, the only one of them she thinks she can trust.

June begins to uncover secrets Lily's closest friends would prefer to remain hidden, and when it becomes clear Lily's death wasn't an accident, June realizes that the only way she can find out what really happened is to revive Murder Club and set a trap. To catch her sister's killer, she will have to host the deadliest Murder Night of all…