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.

As the secrets revealed get darker, Alison becomes harder to read, and Mia starts to wonder - why is Alison so keen to help? And then a piece of the puzzle appears in an impossible place, and Mia has to ask, is she losing her mind, or should she be afraid for her life?