A ship named the "Hanover" in the arctic circle picks up a long forgotten signal seeming to have just appeared coming from a numbers station somewhere deep out at sea. The captain of the survey ship decides to contact the Project Director, Jael Altland.
After having a dangerous encounter with poachers on her Wild Life Preserve in Tanzania, Jael contracts a pilot, Virgil Teague, with the only sea plane in the area. A day later they meet up with the crew on board the ship and learn all of the details. A strange and eerie signal similar to a numbers station, keeps repeating from an undisclosed location nearby. The signal is interfering with their sonar equipment and has to be shut down. After tracking the signal to an empty part of the ocean, her and her pilot, Teague, fly out to see what is there.
They discover a giant ice berg at the location, which explains why nothing showed on the map. Teague finds a concealed entrance leading down into the ice. Upon entering the depths of the ice berg, they find a gigantic and secret U-Boat! They are inside a forgotten top secret German submarine pen!
As the crew combs over the antique vessel they learn that the Germans have harnessed the power of the atom, but not in time to win the war. The sub is armed with eight atomic torpedoes. A set of weapons that has been sought after since the end of the war by a group called the Sword of Legion, who had been watching her and other research companies, waiting for one of them to make this discovery. The man responsible for the poachers at her preserve, Benton Grey, is their primary. He had been a thorn in her side for this one reason all along.
Stranding Jael, Teague, and the crew on the melting ice berg, Grey and his combat teams steal the U-Boat and set out to start a war that will pave a path to victory for the Sword of Legion. Another submarine, a resupply vessel, is found in a closed off part of the ice, also left behind. Jael and her crew outfit it and get it started using fuel from the research ship. With only a few operable torpedoes, Jael sets out to stop Grey.
Grey’s boat is already achieving its first atomic kill when Jael and Teague manage to contact the Navy about the cause of the explosion. The Navy disregards them until an entire fleet is eliminated out at sea. In a wild and desperate showdown between antique relics of the past, Jael and Grey battle it out on the tide.