Cassie and Sunny join together to investigate when a body is found in a suitcase when the river Lea gets dredged.

With their victim now identified, Cassie and Sunny's search for David Walker's killer is underway.

With Sara's revelation about her past to her husband sending shock waves through their domestic bliss, she fights to make him understand.

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 David Walker, Cassie and Sunny try to join the dots to discover who actually killed him 25 years earlier.