What could possibly keep Lewis Tiggle from enjoying his twelfth birthday and the last day of school before summer vacation? Having his sister, Lallie, under foot might spoil his special day. But what he doesn't know is that together with Lallie, their precocious cat, and a friendly mouse, they'll all be sucked into a watery hole in the wake of a very strange storm that strikes their seaside village of Mousehole, England. A terrifying voyage through the depths of the ocean takes them to a mysterious place called Pood: a hostile, threatening land filled with secrecy and oddities. When they learn that three Topland children are being held captive in Pood, a race begins to rescue them and find a way home. But finding a way out is not so easy when you're trapped under the sea in a place that brings things in, but never lets them out.