Morse collapses during a conference on Victorian crime and is admitted to hospital. To pass his time in bed, he reads a book about the famous Oxford Canal Murder of 1859. A young woman was found dead in the canal, and the local police believed she was the victim of four rough boatmen who were carrying her by barge to London. A murder trial resulted in two of the men being convicted and hanged. Morse becomes convinced there was a miscarriage of justice and he enlists the help of a young police recruit, as Lewis is away on a training course. They trace the physical evidence from the crime, which is still stored in a local archive, and subject it to modern forensic tests. The results lead Morse to unearth an insurance fraud which was the motive for the framing of the boatmen - a fraud which is confirmed by a visit to a neglected grave in Ireland.