Danger Mouse and Penfold accompany Professor Squawkencluck to the Brainiac Symposium, the annual science convention, where King Kong Brunels's latest misfiring invention, the Cow Trainer, reminds his fellow boffins exactly why he is the laughing stock of the scientist community. When King Kong Brunel suggests that the Professor's success is all due to her privileged life as Danger Agency lab technician with scientist parents, an irked Squawk uses Brunel's Cow Trainer to swap bodies with him in order to show that she could be just as successful in his shoes.

In the midst of an interstellar team-up, a bickering Danger Mouse and Jeopardy Mouse crash-land on a desolate planet. While Penfold, Squawkencluck and King Kong Brunel search for a way to bring the pair back to Earth, the stubborn pair split up in their new surroundings. DM and Jeopardy Mouse are brought back together when they're captured by a horde of Fly People - the planet isn't deserted after all! The Fly People's hatred of DM is explained when our hero is reunited with Lionel the huge World Wide Spider, who he accidentally sent to the planet of the flies. Lionel's fondness for snacking on the local population has landed him a place on the menu - he's going to be fed to the terrifying pit-dwelling 'Beast', and now DM and Jeopardy are going to be eaten too! Will DM and JM finally resolve to co-operate to get out of this perilous position?