A boxer confesses to killing her manager, but the detectives think she may be covering for her father; when a suspect accuses David of planting evidence, he's devastated to realize the team has doubts, and he makes a decision about his future.

A delivery driver is killed, and a trace of his movements places him at a pub that his wife frequents; she has a motive, but she's an alcoholic and can't remember if she killed him or not; when David doesn't turn up for work, Vivienne confronts him.

After young medical student Japesh Patel is stabbed to death, Billie wonders if it's connected to a similar, non-fatal attack on a gang member. Meanwhile, tensions between David and Vivienne reach a breaking point.

When Major Len Miller is found dead at the bottom of his stairs, a bloody fingerprint implicates his grandson; as David and Vivienne shed light on a dark secret from the major's past, they also must deal with the fallout from their indiscretion.

DC Rob Brady wakes up in his car with a witness lying dead next to him and is arrested on suspicion of murder; in his eagerness to clear Rob's name, DI David Bradford interferes with the investigation against DS Vivienne Cole's advice.