Laura Poindexter, a rich American tourist, dies in the Randolph Hotel, Oxford, apparently from a heart attack, but Morse suspects foul play. Laura was due to return a historic jewel to an Oxford museum, and it has gone missing. Then Dr Kemp, who is a womanizing historian, dies of a fall, Lucy Downes is crushed to death in a telephone box, and Dr Kemp's widow appears to take a fatal overdose of Paracetomol. Morse believes the deaths are all linked.

Jane Robson asks Morse to present a crossword prize at a summer school in Lonsdale College, and while he is dining with a group of overseas students, a young Japanese man dies in what seems to be a brutal ritual killing. It turns out that Morse has unwittingly given all his best suspects a watertight alibi. Morse is attracted to Jane Robson, although she is plainly a neurotic woman who suffers from mood swings and even temper tantrums. He finds that Jane's grandfather was a prisoner-of-war in the hands of the Japanese during the second world war, and he begins to suspect a complicated conspiracy.