An asteroid is steaming towards Earth and the world's greatest scientists - and Isambard King Kong Brunel - are called together to come up with a solution. Squawkencluck invents a size-changing device which is stolen by the ever frustrating Brunel who intends to use it to make himself taller. In the furore Penfold is accidentally zapped and made massive. Penfold panics and runs away but it's quite hard to hide when you are 1000ft tall. For once the world is relying Penfold to save it so can DM calm the gigantic Penfold long enough for him to deal with the asteroid?

Ian, DM's biggest fan, wins a competition to hang out with our heroes for the day. Unfortunately for Danger Mouse he must do everything 'safely' in order to avoid Ian being injured. The last few Danger Fans ended up in a bad way. It soon becomes clear that Danger Fan isn't all he seems and he's snatching and shrinking members of our show for his own collection. DM must infiltrate his greatest fan's lair to save his friends and his foes in a Lilliputian battle royale! Danger Fan is delighted to become an arch villain!