In Tummen gets a friend, he finds a strange thing on the ground when he is out and about. What can it be? A sausage? A thick rubber band? A thread? No, it moves and is a damaged caterpillar. The thumb saves the caterpillar from being eaten by birds, frogs, ants, spiders and beetles. The larva is allowed to live at Tummen's home. It's hungry. The thumb offers all the food he can find, but not even ice cream the caterpillar likes.