One girl's dead. One's in hospital. And one has a secret. Paige, Sarah, Jess and Tallulah were best friends at school. Now they've begun university and are living together at college, but it's not turning out like it's meant to. Tallulah's partying too hard, Jess is being secretive, Paige is embarrassing herself with an unrequited crush, and Sarah's struggling to keep up with her wealthier friends. One night, Sarah saves Paige from drowning in the university swimming pool. Paige can't remember why she was there, and Sarah's too afraid to say what she thought she saw. Then Jess's body is found outside the college laundry. It's not until Sarah meets the gorgeous and charming Jonny that she can tell someone her suspicions. But what really did happen that night at the pool? And what connects Paige's accident with Jess's death? As Paige starts to piece together her memories, the most terrifying question becomes clear: could it be happening again?