Three men, carrying strange tools in their backpacks, are searching for a hot spring in Moominvalley to prepare for the construction of a spa. Sniff is immediately interested and tries to help them, because he expects to get rich without much work with the help of the spring. However, the Moomins are suspicious of the newcomers, as no one likes the idea that Moominvalley could one day be populated by tourists. They therefore enlist the old witch as their ally. With her magical powers, she is supposed to drive the three men away.