Unforgotten

A body in a suitcase is found at the bottom of a London river. As Cassie and Sunny try to identify the victim, four unconnected people go about their business -- all unaware they are about to be dragged into the investigation.

With their victim identified, Cassie and Sunny investiage David Walker by talking to his ex-wife, DI Tessa Nixon. A search through the original files and some numbers from David's pager also lead to new suspects.

Further investigation into David Walker's life suggest he was a troubled man. Marion has a prickly chat with Cassie. As the investigation encroaches on their lives, Sara and Colin open up to their partners about their past.

Marion jeopardizes her marriage; Colin is blackmailed even further; and the secrets of Sara's past push her family to breaking point. Tessa is called in for questioning again, which threatens her relationships with her family.

Cassie turns her attention to Brentford House and the theory that the suspects may have been abused at the gatherings there. The detectives question Marion again, and look further into the accusations made against Colin.

With the suspects all having either motive, opportunity, or a connection to the victim, Cassie and Sunny are left with a massive puzzle to solve, and the team must consider the possibility of a wider revenge plan.