Power-hungry tiny alien Empress Miasma takes control of Gnasher from the inside and uses him in her attempts to take over planet Earth. But when Miasma breaks out of Gnasher into Beanotown for real and Walter helps her grow in size, mayhem really takes hold!

A snake bite causes Grizzly Griller to forget all his survival know-how, so it's down to his greatest fan Dennis to help him re-learn his survival skills so they can all make it safely back to Beanotown.