Summary: The text describes an episode in Moomin Valley where Moomin and his family set out for a nearby lighthouse. They encounter a fisherman who mentions the lighthouse has never been operational and is deserted. Curiosity leads them to the lighthouse, which appears abandoned. A horrifying story about a potentially sick lighthouse keeper emerges, but it's unclear if it's true.
Here are the key facts extracted from the text:
1. The lighthouse on the island was not working, and there was no lighthouse keeper.
2. Moomin and his family arrived on the island, looking for answers about the lighthouse.
3. They encountered a fisherman who mentioned that the lighthouse had been empty for a long time.
4. The fisherman described a terrible situation where the lighthouse keeper had scurvy and couldn't move, with no one to help him.
These facts provide an overview of the situation and the mystery surrounding the lighthouse and its keeper.