Morse and Lewis delve into the mysterious death of Laura Poindexter, an American tourist who had been part of a high-end tour group visiting Oxford. Initially thought to have died of natural causes, Morse is convinced there is more to the story. As they investigate further, they discover that Theodore Kemp, the Ashmolean Museum's expert on the Wolvercote Tongue, has also gone missing, leading them to believe that the two deaths are connected.