The jewel that was ours

A group of American tourists are staying in Oxford, as part of a tour visiting several towns in England. One of them is found dead in her hotel room. Her pocketbook, containing a priceless artifact which was to be donated to Oxford's Ashmolean Museum, has been stolen. Detective Chief Inspector Morse and Sergeant Lewis are called in and within days, there is another murder. This time, the victim is the very person who was to accept the donation on behalf of the museum. What is the mystery surrounding the artifact, the "Wolvercote Tongue", that would cause such deadly events to take place? Morse and Lewis will get to the bottom of it, unravelling every clue and exposing more than one guilty secret along the way.