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.