In different parts of London, three recruits prepare for their first day at the Metropolitan Police's training centre at Hendon. All three have secrets in their past they are keen to behind them. But the Met has other plans for Jamie, Bunny and Tina. They are to join a team of undercover detectives, a secret unit involved in the long-term penetration of criminal gangs. Their target? One of the world's biggest drug dealers: Den Donovan - alias "Tango One". A man so rich and powerful he's virtually untouchable, despite being number one on HM Customs and Excise list of most wanted criminals. But as the three recruits close in on their quarry, they are unaware that someone is pursuing an alternative agenda. Someone who has deliberately put their lives on the line...