Philomena McCarthy has defied the odds and become a promising young officer with the Metropolitan Police despite being the daughter of a notorious London gangster. Called to the scene of a domestic assault one day, she rescues a bloodied young woman, Tempe Brown, the mistress 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 Phil's father and to the detective is found floating in the Thames, Phil doesn't know where to turn, who to blame or who she can trust.