Inspector Morse is admitted to the
John Radcliffe Hospital in
Oxford with a
perforated ulcer. Early the next morning, another patient in the same ward, Colonel Wilfred Deniston, dies. In the evening, Morse is visited by Detective Sergeant Lewis, who brings him two books to read: a study of crime and punishment in mid-19th-century
Shropshire (chosen by Mrs Lewis) and a salacious paperback titled
The Blue Ticket (chosen by Lewis himself). Later, Colonel Deniston's widow gives Morse a booklet written by Deniston and titled
Murder on the Oxford Canal, about a 19th-century murder case. Morse reads Deniston's book (the text of which, divided into four parts, is reproduced in full over the course of the novel). It tells the story of the death in 1859 of 38-year-old Joanna Franks, who was found drowned in the
Oxford Canal at
Duke's Cut, close to Oxford. She had been a passenger on the
"fly" boat Barbara Bray, travelling from
Liverpool to join her husband, Charles Franks, an
ostler, who had obtained a new job in London. The boat's crew comprised Jack 'Rory' Oldfield, the captain; Alfred Musson (alias Brotherton); Walter Towns (alias Thorold); and a "
boy", Thomas Wootton. All four were charged with Franks' rape and murder. The charges against Wootton were dropped, but Oldfield, Musson and Towns were found guilty and sentenced to death. Towns received a last-minute reprieve and was
transported to Australia, but Oldfield and Musson were publicly
hanged. As Morse reads, he develops doubts about the evidence presented at the trial, and the soundness of the verdict. He seeks additional information through Lewis, who is sent in search of the original
assize court registers; and through Christine Greenaway, the daughter of another patient on the ward, who works at the
Bodleian Library, and is sufficiently taken with Morse to pursue research on his behalf at the
Westgate Central Library. Lewis discovers that some of the physical evidence from the Franks case is still held at the City Police headquarters on
St Aldate's, including Joanna Franks' shoes and
knickers. Morse is discharged from hospital, but told to take a further two weeks off work. He continues to ponder the Franks case. He theorises that Joanna had not been drowned at all, but had staged her death as part of an
insurance fraud (her father had been an agent for an insurance company), substituting another body for her own. He further speculates that the supposed death in 1858 of her first husband, F. T. Donovan, a stage
conjuror, might have been a similar fraud. He decides to visit Donovan's grave in Ireland, where, with the help of a local police officer, Inspector Mulvaney, he carries out an unauthorised exhumation. Donovan's coffin proves to contain only a carpet rolled around some squares of
peat. Morse and Lewis then visit the
terraced house in
Derby that had been Joanna's childhood and pre-marital home, and is now about to be demolished. Inside, under multiple layers of
wallpaper, they discover a set of marks recording Joanna and her brother's heights as they grew up: these confirm that Joanna had been considerably shorter than the body found in the canal. In an epilogue, Morse abruptly realises that the name of Donald ("Don") Favant, a passer-by and potential witness in the case who subsequently disappeared, was an anagram of F. T. Donavan: he must have been Donovan using a pseudonym. ==Title==