Tano U Greco has been on the run for 25 years when he decides to surrender to Montalbano in secret, pretending to have been discovered. The same night Tano is caught, goods are stolen from a supermarket. A rather strange theft as the Tir with stolen goods is found a few kilometers from the place of the theft. Despite all the precautions, however, Tano is killed during a transfer and Montalbano, who following indications received from Tano, had discovered a deposit of weapons in a cave, is threatened. Without giving weight to the threats, the commissioner in a subsequent inspection in the cave discovers two fifty-year-old skeletons watched over by a terracotta dog. The situation becomes more and more intricate and dangerous.