The book begins with poor Morse in the hospital suffering from a bleeding ulcer and enlarged liver, the result of all those pints. It's so different from the usual Morse in command; now he's forced to undergo the indignities of the hospital and completely at the mercy of others. He is given a copy of a book detailing the results of the murder of Joanna Franks who had been raped and murdered in 1859. The perpetrators had been arrested and hung. With nothing better to do, Morse reads the book but soon begins to have doubts about the original prosecution. So we have a book within a book. Soon Morse is deep into locating materials from the original investigation.
There are some really charming scenes. Lewis brings Morse a soft-porn novel, The Blue Ticket, a paperback with a titillating cover. One night, after waking up following lights out, he notices that the officious nurse who runs the ward is absent, and he turns his light on -- what harm could it do -- to read this little erotic diversion. Nurse "Cratchett" catches him at it, chastises him for turning the light on and then notices the cover of the book.
Needless to say, Morse solves the century-old crime, much to his satisfaction. The usual excellent language is present. Delightful.