DS Claire Stanton tries to find out if her lover DS John Boulton is working with DS Don Beech, but finds nothing. When their star witness Lynette turns up again, they immediately hide her in a safe house where she reveals that Ray Bazzini killed Rachel Booker. Beech gives Fallon the location of the safe house and two masked men burst in an attempt to seize her. Stanton ushers her out, leaving Boulton to face the thugs, but Lynette runs off again. Beech meets with Fallon, who suggests ways to make Boulton disclose where Lynette is, from bribery to kidnapping and torturing him. Beech agrees to try to persuade him.
Stanton and Boulton spend the night together. She is on the verge of revealing to Boulton her secret assignment with CIB when he gets a phone call from Beech, who needs to talk to him urgently. They meet at a cement works, where Beech admits that he has been working for Fallon and it was him who gave up Lynette's location. He tries to convince Boulton to help him out, for friendship's sake and possibly for money, but an angry Boulton refuses. They fight, and in the struggle, Beech beats Boulton to death. He realises what he has done and flees the scene, leaving Boulton's body behind.
- Russell Boulter as DS John Boulton
- Clara Salaman as DS Claire Stanton
- Billy Murray as DS Don Beech
- Simon Rouse as DCI Jack Meadows
- Shaun Scott as DI Chris Deakin
- Joy Brook as DC Kerry Holmes