1942: the Human Torch goes insane and descends into the ocean, his extreme heat creating an unquenchable path through the water. He comes to Atlantis where he boils the guards alive. Their protectors arrive to battle the Torch—the Nazis in diving equipment, who have captured Captain America and Prince Namor, the Sub-Mariner. Cap thinks back to how this began…
…in a British shipyard the Invaders were fighting off a Nazi bombing raid. Cap was confused by the Nazi foot soldiers’ halfhearted attempts to take the shipyard until the enemy’s real objective became clear: a massive dirigible appeared in the sky and shot down Namor as the tried to take the craft. It then dropped an asbestos net and captured the Torch and the ship’s weird gondola dropped into the water with Namor in pursuit. Cap never saw his allies again. He reported to his commander General Phillips who castigated Cap for his unpreparedness for even as unusual and eventuality as this. An angry Cap realized that Phillips was right. As he left the building he was confronted by an enraged and silent Namor who took him aboard his seacraft for a mysterious mission. As they approached Namor’s home, Cap suddenly understood the reason for his partner’s wrath: the Nazis had conquered Atlantis. Cap dons a diving suit and they go down to explore the situation. Eavesdropping earlier, Namor had learned that the Nazis were seeking the secrets of Atlantean science and promised protection from "the American menace" in return. Caught by guards they fought back valiantly until the overwhelming foe overpowered them. At this point the insane Torch appeared to assault the underwater city….
Cap realizes that the Nazis have interfered with the flaming android’s programming to increase his power as well as to control his mind. Their objective: to win the Atlantean’s trust against the Americans. The city’s ruler Princess Fen arrives and swallows the Nazi propaganda. She accuses the USA of brainwashing the Sub-Mariner into abandoning his people to pave the way for an American invasion and orders Namor and Cap imprisoned. Cap is puzzled by the normally explosive Namor’s submissive attitude until he learns the reason for it: Princess Fen is his mother….