It’s 1955 and Jacques Cousteau and his fellow underwater explorers are anchored above a site in the Red Sea. As one frogman descends to a depth of about 100 feet, he finds a rusting anchor chain. Following it, he comes to a vessel that no one has seen since 1941. It’s the S.S. Thistlegorm, a British merchant ship sunk by German bombers during WWII. And once the divers enter the wreck, what they find stuns them.