It was supposed to be a simple mission. A suspected Russian spy boat is in trouble in Canadian waters. Investigate and report are the orders. But when Captain John Banks and his squad arrive, it is to find an empty vessel, and a scene of bloody mayhem. Soon they are in a fight for their lives, for there are things in the icy seas off Baffin Island, scuttling, hungry things with a taste for human flesh. They are swarming. And they are growing.