A frenzied Sub-Mariner attacks the weakened Iron Man in his lab. Iron Man tricks Subby into throwing him into a reinforced safe room where his is able to close the door and recharge his armor. Sub-Mariner is also in need of a recharge so he flies off to take a quick dip in the ocean. Meanwhile the police arrive at Stark Industries and accuse Iron Man of wanton damage. Pepper and Happy have turned up too. A refreshed Sub-Mariner prepares himself for round two!; Cap rescues a pilot whose plane was shot out of the sky, only to discover he's a member of A.I.M., and he tells Cap about A.I.M.'s "supreme achievement"--The Cosmic Cube--which has been stolen by it's "keeper," who's taking it to his new master...The Red Skull! Watching via remote camera, The Skull uses a "neuro brain-trap device" to brainwash his loyal follower, Wolfgang, into blowing his own brains out! Using an "experimental manned missile" from SHIELD, Cap catches up to The Keeper and leaps in mid-air onto his jet plane. As they battle, the hypnotized man hits the ejector switch, and the two parachute down to a remote island, in view of The Skull. The evil Nazi gains the advantage by telling Cap he was the one who gave the orders that resulted in Bucky's death back in 1945. Gaining the Cosmic Cube, which can "convert thought waves into material action"...he wills The Keeper into another dimension. Cap realizes his foe has now become invincible!