For rookie detective constable Fiona Griffiths, her first major investigation promises to be a tough initiation into Cardiff's dark underbelly. A young woman and her six-year-old daughter have been found brutally murdered in a squalid flat, the single clue a platinum credit card belonging to a millionaire businessman who died in a plane crash six months before. For her fellow cops, it's just another case of a low-rent prostitute meeting the wrong kind of client and coming to a nasty end, but Fiona is convinced that the tragic lives and cruel deaths of this mother and daughter are part of a deeper, darker mystery. Fiona, however, has secrets of her own. She is still recovering from a crushing psychological breakdown, and the feelings which haunt her are constantly threatening to undermine the mask of normality she has learned to wear. As she begins to piece together a bizarre and terrifying conspiracy, Fiona finds that what makes her vulnerable also gives her a unique insight into the secrets of the dead, and in solving the murders of Janet and April Mancini she can begin to start solving the riddles of her own past.