Sea Venture, CV for short, is the largest ocean-going vessel ever built by man. It is not a ship but a huge sea habitat housing a scientific research station, an entire city of two thousand permanent residents and a thousand passengers.For some, CV is the vacation dream of a lifetime; for others, a vision of man's conquest of the seas; for two men it becomes the arena for a deadly game of cat and mouse.But for one, CV is something else: a place to stalk its next victim. It is not human, it is not even of Earthly origin. To be touched by it is deadly.What important are the hopes and dreams, fears and schemes of the people of Sea Venture when they are threatened by a force that could destroy all of human civilization?