Hermit Crab has outgrown his first shell, and, as hermit crabs do, he must look for a new house. Nervous and a little frightened, the crab plucks up his courage and finds a shell that's big enough for him. The only problem is that it's very bare. That's where his fellow undersea creatures come in: a sea anemone offers to decorate the outside, a starfish the inside; an industrious sea snail, a fortress-protecting sea urchin, and an illuminating lantern fish move in as well.