Milo and his friend Valia are busy bickering as usual when all of sudden, giant Jack-in-the-beanstalk type plants rip through the panoply of clouds and come crashing down to Earth. Immediately afterwards, they find a young girl lying unconscious in the river, who turns out to be a princess from a different world. This world, located high above their own, has been invated by hideous screaming creatures that feed on human brain energy, and before you know it, Milo and his friends, followed by two incompetent policemen and a crotchety old farmer, are racing up the giant plant to escape the monsters and try to save their new friend's world.