When Moomin and Snorkmaiden wake up, the floating theater has disappeared. They are alone, surrounded by a vast watery desert. The floating house hits a rock, and the violent jolt causes Little My to fall overboard. The current sweeps them away. To find the lost children, Moominpappa and Moominmamma look for a way to make as many people as possible aware of their fate. Cleaning lady Emma has a good idea: what if everyone performed a new play together? The title would have to be "The Lost Children."