Morse and Lewis investigated the death of American tourist Laura Poindexer, a member of an exclusive tour group that visited Oxford. Her jewels are missing from her personal belongings, including the diamond tongue she plans to donate to the Ashmolen Museum. The pathologist confirmed that she died of natural causes, but Morse felt that something was wrong. The mystery deepened when Theodore Kemp, the wolf tongue expert of Ashmolen, was found dead and Mrs. Poindexter's husband disappeared.