Pete Ashton is an undercover detective - tasked with smashing open the most dangerous drugs gangs blighting Britain's streets.He targets hardened criminals - men at the top of their game, who have everything to lose, and who would not hesitate to put a bullet in his head if his cover is blown. Crack gangs, heroin dealers, speed freaks - he's infiltrated them all, and put many of them behind bars. This is the story of a life lived in the shadows - always looking over your shoulder, pushing yourself and your cover story to its limits - and the toll it takes.