Despite being the daughter of a notorious London gangster, Philomena McCarthy has defied the odds and become a promising young officer with the Metropolitan Police. Called to the scene of a domestic assault, she rescues a young woman: Tempe Brown, the girlfriend of a decorated detective. The incident is hushed up, but Phil has unwittingly made a dangerous enemy with powerful friends. Determined to protect each other, the two women strike up a tentative friendship. Tempe is thoughtful and sweet, and makes herself indispensable to Phil; but sinister things keep happening, and something isn't quite right about the stories Tempe tells. When a journalist with links to both Phil's father and Tempe's boyfriend is found floating in the Thames, Phil doesn't know where to turn, who to blame - or who she can trust...