Unforgotten

As the detectives begin identifying the victim found in the river, four unconnected people go about their business unaware they are about to be dragged into the investigation.

With the victim identified as David Walker, Cassie and Sunny talk to his ex-wife, DI Tessa Nixon, who reveals he suffered from depression.

Sunny makes further investigations into David Walker's life that suggest he was a troubled man with a number of issues.

Marion jeopardises her marriage by refusing to open up about her past, Colin is blackmailed even further and the secrets of Sara's past push her family to a breaking point.

Cassie focuses on the theory that suspects may have gathered at Brentford house. Marion is questioned again after Sinead's allegation that David could have been an IRA target.

All the suspects in the David Walker murder have a motive, opportunity, or connection to the victim - leaving Cassie and Sunny with a massive puzzle to solve.