78-year-old balloon salesman Carl Fredricksen finally fulfills his lifelong dream of a great adventure when he ties thousands of balloons to his house and flies away to the wilds of South America. But he discovers all too late that his biggest nightmare has stowed away on the trip: an overly optimistic 8-year-old Wilderness Explorer named Russell. Their journey to a lost world, where they encounter some strange, exotic and surprising characters, is filled with hilarity, emotion and wildly imaginative adventure.