Charles Muntz is a renowned explorer who claims to have found a new species of giant bird in Paradise Falls, South America. However, archaeologists study the bird's skeleton and conclude that Muntz is a cheat. So Muntz vows to capture a live specimen.
Meanwhile, young Carl Fredricksen meets Ellie. Both are aspiring explorers who idolize Muntz. The two eventually get married and save for a trip to Paradise Falls, but they always end up spending the money on more pressing needs. As an old man, Carl finally buys tickets for the trip, but Ellie falls ill and dies before they can leave ...
But Carl continues to live in the house he and Ellie created, stubbornly holding on as the neighborhood around him is replaced by skyscrapers. When he accidentally injures a construction worker, the entrepreneur trying to buy his home takes the opportunity and the court orders him to move to a retirement home. However, Carl decides to keep his promise to Ellie and turns his house into a makeshift airship by attaching hundreds of helium balloons to it (having worked as a balloon salesman), and sets off for Paradise Falls with Russell, a young scout..