Muzzy, the friendly green clock-eating monster from outer space, returns for more adventures with his friends in Gondoland. Everyone expects him, and King Nigel and Queen Ezra decide to arrange a ball for the christening of Bob and Sylvia's new baby daughter Amanda. Meanwhile, servant Corvax invents an invisibility device and, with his assistant named 'Thimbo (the Terrible)', a thief on parole, plans to kidnap Amanda, to get revenge on Bob for tricking him and taking Sylvia away from him.
Corvax and Thimbo succeed in kidnapping Amanda and they get away on Nigel's yacht. However, Amanda sinks the boat by pulling the plug out of the hull. The three manage to survive and they go to Corvax's hideout – a small hut which in fact turns out to be Corvax's operations centre. Meanwhile, Muzzy, Nigel, Ezra, Bob and Sylvia follow Corvax's trail, recover Nigel's yacht and track Corvax to his hideout.
At the same time, Corvax and Thimbo have a problem: Amanda gets hungry and wants to eat; while preparing the food, Thimbo lets the invisibility device loose and it is picked up by Amanda, who activates it. Corvax and Thimbo try to find Amanda, but fail. Muzzy, Nigel, Bob, Ezra and Sylvia enter the hideout and confront Corvax. Thimbo confesses to Nigel that this hut is an operations center. Meanwhile Amanda is found but she cannot be seen. Muzzy constructs another invisibility device and uses it to make Amanda visible. All then go back to the palace. In the end, Corvax and his coward friend Thimbo ride with sheep, to receive the unknown ultimate punishment offscreen.
- Jack May as Muzzy (a furry greenish blue extraterrestrial) and Norman's friend (a human)
- Willie Rushton as King Nigel (a lion) and Additional Voices
- Miriam Margolyes as Queen Erza (a rat), Norman's wife (a human) and The Servant Maid (a bulldog)
- Susan Sheridan as Princess Sylvia (a rat), Amanda (a rat) and Additional Voices
- Derek Griffiths as Bob (a mouse), Corvax (a green goblin) and Additional Voices
- Peter Jones as Thimbo the Terrible (a bulldog), Guest #1 (a mouse) and The Shepherd (a pink goblin)
- Benjamin Whitrow as Norman (a human)
- Directed by: Richard Taylor
- Executive Producer: Joe Hambrook
- Original English Scripts: Wendy Harris, Joe Hambrook, Richard Taylor
- Language Course Designer: Diana Webster
- Animation: Richard Taylor Cartoon Films Ltd.
- Additional Animation: Bob Godfrey Films Ltd.
- Music by: Peter Shade
- Produced by Richard Taylor Cartoon Films for BBC English by Television