When Nazi submarines prowl mercilessly around the Atlantic, their series of successes proved to be only temporary: the American forces are finally taking over. US warships, grouped in huge convoys, are launching a coordinated counterattack, and giving the death blow to Hitler's underwater terror. Today, the research team maps dozens of wrecks from this forgotten WW2 battlefield and dives deep, determined to uncover a ghostly German submarine that became an eternal tomb for its crew.