Felix had a feeling that something was wrong. ‘It's my cousin Terrance,' he squeaked. ‘I think he needs my help.' As he sets out to find Terrance, Felix rescues a pelican in the park, and Amos, a little mouse, dangling from the jaws of a cat. After finding Terrance, he introduces him to Amos where it is love at first sight. After escaping from the clutches of Sir Oswald, the biggest rat around, they head back to Buckingham Palace, where Felix has invited them both to live. On the way home, they pass Covent Garden where they help Jim save his merchandise and an old lady who gives them each a balloon in return for their kindness. The balloons prove too much and carry them high into the sky on another adventure. Will this be the end for the three little mice or will they arrive home safe & sound?