The Moomins have grown up: their lighthouse and their island in this episode are the property of adults as well as children. Tired of the easy life of Moominvalley where Moominmamma runs everything and Moominpappa feels useless, husband and wife set off with Moomintroll and Little My for the lighthouse which awaits them. The Groke, who is everything cold and deadly, follows. They all have trouble adjusting to the new home, but finally a storm comes, bringing the island itself to life in fear of the sea. The Moomins and the anti-social fisherman draw together in the lighthouse, while bushes and trees sock shelter close by; the fisherman turns out to be the lighthouse keeper. The sea gives Moominpappa a carton of whiskey and some driftwood and they become friends, Moomintroll dances with the Groke and makes her warm, Moominmamma is no longer homesick, and the returned lighthouse keeper turns the light on. The Moomins have regained the feeling ""that it's always Sunday""; Pappa says ""It's just that feeling that we had lost."" A psychological drama with an allegorical level, this chapter of the Moomin story cedes Moomin territory to the adults without totally dispossessing the children.