Unforgotten

Further examination of David Walker's history suggests that he was a troubled man with a number of issues. Marion has a prickly chat with Cassie about her past and the investigation reveals her close relationship with an IRA activist. As the police enquiries encroach on their lives, Sara and Colin open up to their partners.

A disturbing allegation about David opens up a second line of enquiry for the team. How much Tessa actually knew about David's life threatens to ruin her relationship with her husband and son. Marion gets into trouble at work and jeopardises her marriage by refusing to open up about her past. After having his phone stolen and information exposed, Colin is blackmailed again - and Sarah's secrets push her family to breaking point.

In the penultimate episode of the series, Cassie turns her attention to investigating the goings-on at the Brentford house and the theory that one or more of the suspects may have been abused at the gatherings that took place there.

With each of the suspects having a motive, opportunity or connection to victim, David Walker, Cassie and Sunny try to join the dots to discover who actually killed him 25 years earlier.