As Lucius learns that his friend Marcus spends too much time bringing his master to the bathhouse, he begin to wonder how to build an indoor bath. He once again ends up in modern Japan, this time in someone’s bathtub. Mistaken as a foreign caretaker by the house’s owner, Lucius comes to learn about more modern conveniences. He builds an indoor bath with this knowledge and Marcus is able to bring his work on time for Emperor Hadrian, when his servant learns of the indoor bath, Hadrianus becomes interested of Lucius's work.