An alien pet escapes from a crash-landed spaceship and it multiplies whenever something touches it, making its capture difficult.

Penfold swallows Professor Squakencluck's new pill and is turned into a super hero which causes Danger Mouse more problems than usual as he searches for a lost messenger pigeon.

Penfold and Danger Mouse journey to the center of the Earth to stop a loud noise that originates there.

Danger Mouse is sent to stop Greenback who is behind the theft of America's greatest buildings.

Penfold puts on Danger Mouse's suit and can't get out. From then on everyone thinks he is Danger Mouse. Later, DM and Penfold go to Bratislavakia to find out why all the countries of Central Europe have swapped places. There they fall fowl of a mystical stone that causes people to swap bodies.