Lying, cheating, thieving—they’re the best undercover cops in the business. Liam Ketman (Nick Berry, Heartbeat) and Garth O'Hanlon (Stephen Tompkinson, Wild at Heart) take on false identities to infiltrate society’s underbelly and stop crime at its core. As they put their lives on the line, Liam tries desperately to hold his marriage together, while Gareth keeps his personal life a mystery.

Tank is an investigative reporter and jailbird, framed on scant evidence supplied by the London mob. Helen is the sensuous call-girl who offers Tank ammunition and retribution. But, retaliation is swift and brutal, in the guise of Sir Robert Knights and his equally lethal lawyer, Dunboyne. A series of hideous murders follow as the devil protects his own. Only Malling and Helen can halt the onslaught. But, for how long, and at what price?