A Russian nuclear-powered submarine, armed with rocket-propelled torpedoes, sinks in the icy water of the Bering Sea, far above the Arctic Circle. Was the cause an explosion? Did it strike some massive, unidentified underwater object? Was it rammed by an American spy sub, as the Russians first suspected? Perhaps it was sabotaged by terrorists? Deep-sea investigators, armed with new forensic technologies, hunt for the answers. An American trawler sinks...