A derelict hotel. A hidden body. A girl who has not been missed. When disillusioned detective Nia Tremeyrick stumbles upon a 30-year-old cold case in her Pembrokeshire seaside town, she relishes the chance to prove herself to her arrogant male colleagues. But with the identity of the victim remaining a mystery, and her own family drama dragging her down, she is struggling to piece together the truth. Meanwhile, back in 1984, bookish teenager Cerys Pritchard is expecting an uneventful summer, until she is persuaded to attend an illicit party in an abandoned hotel by her rebellious new friend Kay Abbot. By the end of summer, one of them will be dead. As Nia digs deeper, she fears the case that was supposed to make her career will turn out to be her worst nightmare. But who was killed that deadly summer? And why?