The world is under attack from invincible, giant Nazi monsters and Allied Command are ready to surrender, when out of the blue they receive a strange telegram from a man called Gibraltar, who claims to be from the lost city of Atlantis. Gibraltar claims that the Atlanteans have developed a weapon powerful enough to destroy the Nazi monsters and all they require is some refined uranium to complete the device. On their way to deliver the uranium to Atlantis in the Danger Submarine, Danger 5 comes under attack from perils of the deep, resulting in Jackson and Claire being separated from the team, feared dead. Ilsa, Pierre and Tucker reach the strange sanctuary of Atlantis and deliver the uranium, however, Gibraltar is not as friendly as he appears to be.