On Martin and Sylvia's weekly trip to the library, they find a book about an explorer named Magellan. The stories in the book inspire them to want their own adventure when they get back home. But it is too cold and snowy outside to use their playhouse. In fact, it is too cold to be outside for long at all. So they transform the living room into a mighty sailing vessel — and oh, what surprises are found by these two daring explorers!