Lucius is tasked to build a new bathhouse for the Emperor's adopted son and heir Lucius Aielus Caesar, but accepting this project makes his wife Livia leaving him for good. While not happy with Aielus's behavior, Lucius goes to the Baths of Trajan to meditate about it but he ends pushed to the water by a group of children playing there. He resurfaces into a water park in Japan where he learns about slides, pools for kids and wine baths. His new bath house becomes a success bringing popularity to Aielus, while also bringing the kids and adults a place to have fun with water.