This was the second part of the first appearance of Arkon the Imperion, who by this point had kidnapped a bunch of nuclear scientists and the Scarlet Witch, in an effort to destroy earth to recharge the energy rings that gave heat and light to his world, Polemachus. It would set the pattern for most of his later appearances: even with the best of intentions, Arkon always chooses the most violent way available to do something, and usually tries to kidnap a babe while he's there. The Avengers are trying to use a "d-machine" to travel to Polemachus after him, but haven't licked their power source problem yet; much to the irritation of Quicksilver, who wants his sister back. And because things weren't melodramatic enough, the Black Widow returns, but only to break up with Goliath, tearfully telling him she never loved him.
Arkon intends on keeping the Scarlet Witch as his bride, and uses "the Ultimate Persuader!" to suck nuclear secrets out of one of the scientists, which cows the others. They make what looks like an atomic superball for him, that when thrown at the right spot on earth, will destroy it but keep the lights on in Polemachus for centuries. Arkon lies to Wanda, telling her the scientists figured out how to not blow up earth, but she still had to stay. Picking a flower, Wanda admits she could almost be attracted to Arkon, if he wasn't so cold and unfeeling. (And smelly. There has to be an almost-visible musk cloud following that guy around.) But no time for love, as the Avengers arrive! With Thor's help, they had been able to get there; either with or without the d-machine. Arkon's barbarian army is no match for an A-list Avengers team that was fighting mad, but his vizier advises, lose the battle but win the war: blow up earth, that'll learn 'em. Wanda realizes Arkon had lied to her, but gets dragged with him as he uses his golden thunderbolts to travel to the Empire State Building.
Thor was able to get four Avengers back to earth quickly: Goliath, Black Panther, Vision, and Quicksilver. And they make a fairly poor showing, stopped one-by-one; with Arkon finally getting Goliath in a brutal judo-like hold. But, before Goliath is forced to tap out, the vizier sends a floating-head message: no need to blow up earth after all. Thor and Iron Man were able to recharge Polemachus's rings--at least for now! Arkon confesses to the Scarlet Witch, the trips back-and-forth from earth and Polemachus should have restored her mutant powers, so he couldn't force her to marry him, and he disappears as the other Avengers return. Still, with a flower as a keepsake, Wanda seems to ponder what could have been.
Arkon is such a dick; I can't stand him. So of course I'd love a Marvel Legend of him!