Jon Arbuckle (Breckin Meyer) goes to London to be with Liz (Jennifer Love Hewitt), and Odie and Garfield (Bill Murray) sneak along with him. Meanwhile, a deceased Queen gives everything to her cat Prince XII (Tim Curry). Her only heir, Lord Dargis (Sir Billy Connolly), becomes jealous and tries to kill Prince. Garfield and Odie sneaks out to the streets of London. Lord Dargis throws Prince in the river and he ends up in the sewer of London. Smithee the butler (Ian Abercrombie) believes he found Prince, but it was really Garfield, and Jon finds Odie with Prince, and mistakes him for Garfield. Now, the castle animals must keep Garfield safe and keep him thinking he's royal to save their lives.