On the North Wales coast two people traffickers are brutally murdered; a drug dealer is mown down in inner-city Stockport and in a remote Pennine cottage a police informant is shot dead. Seemingly random, these murders are the work of one professional hitman. Reluctantly, Marie Donovan takes on another undercover role and finds herself working with DI Jack Brennan, a high-flying detective with a tarnished career. Soon, mistrustful of each other and their superiors, both begin to suspect that they are mere pawns in a complex game of criminal rivalry and police corruption. Marie finds herself with no friends, no-one to trust and nowhere to hide.