Three senators, envious of Hadrian's success with the thermal baths, decides to get rid of Lucius by sending him to investigate a good place to put a bathhouse near Mt. Vesuvius. Lucius, unaware of the danger, ends surrounded by bandits. Lucius convinces them to help him build a bath and everyone ends enjoying the place. When the bandits wonder if they really found a treasure, Lucius slips into a modern hot spring town in Japan, where he learns that the economy of the place is not only based on the hot springs, but also in the food and the souvenirs sold there...