Grub is a little monster with a big problem – he's absolutely terrified of humans, especially the one his brother says lives under his bed. Grub's mum says there's no such thing as humans, but even so, they must never go to the edge of the forest. That's fine by Grub, until his brother dares him. He can't refuse a double dare, can he? Will Grub find humans at the edge of the forest … or something even worse?