A car lies crashed below a Welsh mountain road. One of the young women inside it is dead, the other badly injured, with no memory of who she is or what just happened. All she has is a bus pass showing her photograph and a name she doesn't recognise.

As she struggles to recover from her injuries, a startling revelation shatters everything she thought she knew, forcing her into an uneasy alliance with Detective Bronwen Pryce. With danger closing in from all sides, the two women must work together to uncover the truth—even if it kills them.