Karen is a refreshingly normal and charmingly unfashionable young woman – slick, maverick cop she is not – but her quick mouth and ingenuity make her an impressive investigator. Following her promotion to Police Scotland’s Historic Cases Unit, Karen is tasked with reopening the investigation into a murder that has been the subject of a provocative true crime podcast. When teenage barmaid Rosie Duff was stabbed to death in 1995, suspicion fell on the three drunken students who discovered her body. But despite police suspicion, the boys were never charged.