When an armoured security van is found at the bottom of a lake, a link's made to a man who disappeared 17 years ago.
Michael Dudley's disappearance coincided with the murder of Marie Sinclair. With the discovery of the van revealing that it was ransacked whilst underwater, and Marie's murder remaining unsolved, the team decides to reopen the case.
The chief suspect at the time, Marie's husband and owner of the security firm, Andrew Sinclair (Peter Hugo-Daly), continues to insist he's entirely innocent. But his story doesn't quite add up.
A visit to the new owner of the security firm, Steve Palmer (George Baker), doesn't provide Gerry with records he was hoping to find. However, it does result in Palmer making the cash-starved Gerry an offer he can't refuse.
Elsewhere, Brian looks into the dive clubs that would have had access to the lake over the years, leading him to diving instructors Martin Viner (David Harewood) and Trisha (Claudia Harrison).
Frustrated by the pace of the investigation, Sandra decides to make the dive herself to take a closer look at the van. It's a risky strategy, but could it provide the team with a vital clue? Or will another murder prove a final blow to the investigation?
