In Deep (2001)

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.