Detective Superintendent Sandra Pullman heads The Unsolved Crime and Open Case Squad (UC0S), cracking previously unsolved crimes from the past. Her team are three ex policemen; Gerry Standing, Jack Halford and Brian Lane, who for various reasons all opted for early retirement. The team tries to prevent Jack from making the biggest mistake of his life, with near-disastrous consequences for them all. They investigate a suspicious death in a nursing home; discover the treasures of a sunken armoured van; uncover secrets in the world of male modelling; and even find themselves investigating a case of spontaneous combustion. Unconventional methods and breaking of the occasional rule, together with technological advances mean UCOS get good results. However when Sandra discovers her colleagues have been less than truthful about important details of her father's career, can the team pull together and put the shocking revelations behind them?