Up follows Carl Fredricksen who had a long life with Ellie and briefly shows their whole life: they fell in love when they were young, both idolizes Charles Muntz, an explorer, and after a miscarriage, the two decide to save up money to go on a trip to visit Paradise Falls. However, they had mishaps and have to dip into savings. It was too late when Ellie grew ill and passed away.
In the present, Carl is an old man who is facing a change in the neighborhood, homes were taken down and turn into businesses, and refuses to move to a retirement home. A boy scout named Russel tries to offer help to Carl in hopes of earning a badge for helping the elderly. One day, Carl finds a man who backed his construction vehicle into the maibox that he and Ellie had painted. The construction worker tries to help Carl by fixing it. Yet, Carl refuses to let the man help him, and he was so tense, he struck the man with his walking stick on the head, causing him to bleed. Days later, Carl gets a court summons and eventually loses the right to his house. When the retirement workers arrive to help escort Carl, Carl decides to leave with his home by using tons of balloon as he flies out of the city.
Carl then finds Russel had sneaked aboard his house when Russel was trying to find something to help Carl. The two eventually arrive to Paradise Falls. As they move the house like a parade balloon, they encounter a strange bird and a dog with a talking collar, Dug. During the walk, Carl gets annoyed with Dug and the bird which Russel calls Kevin. Despite his efforts, he cannot shake them off. Eventually, they arrive to a cave where they find Charles Muntz who invites them to dinner. After Charles Muntz shares his story of struggling to find the bird, Russel blurts out that the skeleton looks like Kevin. As Charles rubs the hats of explorers and asks Carl about his adventure, Carl tries to leave and shuts Russel up since Russel doesn't read the situation. Suddenly, Kevin calls outside of the blimp, alerting Charles to call out his dogs to chase after Carl's group.
Despite their efforts, Charles tracks them down using the GPS in Dug's collar and tries to burn the house to distract Carl. After Charles steals Kevin, Russel is mad at Carl for saving the house instead of Kevin. While Carl tends to his house, Russel decides to take some balloons and chase after Charles's blimp himself. Carl, realizing what he had done, decides to go after Carl by throwing everything out of his house to make the house lighter to fly. During the chase and battle, Charles ends up dropping to his death with Carl's house as they Carl manages to trick Charles in saving Dug, Russel, and the bird.
Later on, Carl attends Russel's scout ceremony where Carl personally puts a badge of helping the elderly on Russel.
- Edward Asner as Carl Fredricksen
- Christopher Plummer as Charles F. Muntz
- Jordan Nagai as Russell
- Bob Peterson as Dug and Alpha
- Pete Docter as Kevin
- Elizabeth Docter as Ellie Fredricksen
- Delroy Lindo as Beta
- Jerome Ranft as Gamma
- John Ratzenberger as Tom