It was supposed to be the perfect reunion: six university friends together again after twenty years. Host Ali finally has the life she always wanted, a career she can be proud of and a wonderful family with her college boyfriend, now husband. But that night her best friend makes an accusation so shocking that nothing will ever be the same again.

Rachel lives a quiet life in the peaceful countryside, content with her perfect man and her lovely dog. But when she stumbles upon a body in the woods one day, all that shatters. She knows what she has to do: run. Don’t get accused of murder. But when this victim is identified as her boyfriend’s estranged wife, Rachel realises she’s already the prime suspect. With mounting evidence against her, Rachel’s only hope is to keep her past well hidden.

Mia Hamilton lived the perfect life with her husband, university teacher Zach, and their two-year-old daughter. But everything changed when Zach committed suicide on the same night one of his students vanished. Five years later, just when Mia is beginning to heal, stranger Alison walks into her life, saying her husband didn't kill himself. Fragile, slight Alison leads Mia on a path into Zach's past, and Mia begins to think she never really knew her own husband.

With two young children, Mary hasn’t slept in what feels like years. For his part, Tim never feels safe enough to sleep. And so one hot, exhausting night, the two strangers meet while seeking solace in a nearby park. There, they witness something horrific: a violent attack in the window of a neighbouring house. Bonded by what they’ve seen, Tim and Mary are desperate to find answers. And when they see news reports of a missing woman who was last seen walking alone not far from them, the pair are convinced it’s her they saw being attacked—no matter what the police say.

Medical student Amy Brenner is spending the night on a locked psychiatric ward. Amy has been dreading her evening working on Ward D, the hospital’s inpatient mental health unit. There are very specific reasons why she never wanted to do this required overnight rotation. Reasons nobody can ever find out. And as the hours tick by, Amy grows increasingly convinced something terrible is happening within these tightly secured walls.