Synopsis
Last issue Magneto captured 4 X-Men (Cyclops, Iceman, Marvel Girl and Prof X) and 3 Avengers (Captain America, Iron Man and Scarlet Witch). He gloats to his mutate aide Piper that he has discovered how to use his magnetic power to control the iron in a person's blood. In particular the blood in their brain, and thus control their thoughts and actions. He has his captives under this spell.
The 3 remaining Avengers (Black Panther, Thor and Vision) are returning from San Francisco where they recruited Daredevil and Black Widow in DD#99. They also found Hawkeye there, after he quit the team in #109. Clint had tried to win Natasha back from her new love, but failed. He refused to rejoin the team, and now determines to make a name for himself solo.
Daredevil recalls the last time he was in Avengers Mansion in Amazing Spider-Man Annual #3 (where they asked him his opinion of potential recruit Spider-Man). BW recalls her time with Hawkeye, but she also remembers her husband Red Guardian (who supposedly died in #44).
DD reads (with his fingertips) a newspaper item about a nearby meeting of the Atomic Energy Commission, and the team leap to the conclusion that it will be Magneto's target, because atomic energy is a cause of mutations.
Sure enough Magneto leads his puppets (except wheelchair-bound Prof X) in an attack on the meeting. His only problem is controlling them all at once, as when he forgets about any they stop fighting. But still the Commission members are easy to subdue and are soon under his mental control.
As Magneto's about to take his prizes away in his flying craft, the Avengers arrive. After a brief battle between erstwhile allies, Magneto causes his ship to emit 'octofumes' which blanket the area in a dense black fog. Thor dispels enough of the fumes to enable Panther to see the escaping craft and acrobatically send Daredevil to latch onto it. (I'm sure DD could have done it 'blind' using his billy club.) But Magneto electrifies the hull, and Widow helps save her falling partner with her web-line. Thor sets off in pursuit, but turns back when the villain threatens to order the Avengers under his control to jump out of the midair craft.
Back on the ground T'Challa remembers that dinosaurs were involved in Magneto's attack last issue, and he should be able to track them back to the villain's lair. But he also notices that Vision is missing.
In that underground lair Magneto reveals his cunning plan. He reminds everyone how he organised the Botherhood of Evil Mutants (in the 1st 11 issues of X-Men) and created mutates in the Savage Land (in XM#62-63) (including Piper). Now he intends to use atomic reactors to radiate the country. Most of the population will die, but the rest will be mutants he can rule.
He recalls how he'd tried a small-scale version of this in Amazing Adventures #9-10 where he was foiled by the Inhumans. He now reveals that he was badly injured by the explosion at the end of that story, but he recovered due to an earlier plan. It seems that when he gave Angel a new costume (in XM#62) he had an ulterior motive. This costume has been siphoning off Angel's youthful mutant energy. Yesterday he had mended enough to break into the X-mansion, drug Angel unconscious and steal his uniform. Flooded with stolen energy he was able to control the brains of the other X-Men. He then lured the Avengers into a trap last issue (so he could get hold of Scarlet Witch).
The Commission refuse to help him, but Magneto takes control of their minds again. But meanwhile Panther has tracked the dinosaurs to the area above the cavern, Daredevil feels vibrations from below, and Thor busts his way in. Another battle ensues, where the free Avengers fare better than their controlled foes because Magneto is unfamiliar with all the powers involved (and because he's trying to control multiple warriors). So in the end the villain just takes over all their minds.
Just as it seems he's won, Piper knocks him out with a karate chop from behind. I turns out that Vision merged his intangible body with Piper's during the octofume blackout. He's been biding his time since then, waiting for the perfect opportunity to take control of Piper's mind and body and strike swiftly and surely. He knew that prolonged control of Piper would risk damaging them both. But it was a risk worth taking for Wanda's sake.
In the 1st epilogue Prof X mentally puts Magneto to sleep. And the X-Men wonder where Angel is now, since the Avengers couldn't find him in the X-Mansion last issue.
In a 2nd epilogue the Avengers ask BW and DD to join them permanently. DD declines (because his senses work better outside of a group, and it would be difficult to maintain his secret (blindness) in a group). But BW accepts (she wants time away from Matt to think about their relationship).