Several Avengers – Captain America, the Scarlet Witch and Vision – watch a training fight between Iron Man and the Black Panther when Thor storms in, ordering the Avengers to assemble. He asks them to the communications room and tells Wanda not to look agitated, for this time this chamber will bring her a message of great joy.
The others follow him and the Scarlet Witch sees that at the other end of the communication device waits her brother Quicksilver, who she feared was dead. Pietro apologizes for upsetting her, but he was close to death, unconscious for many days and unable to communicate until now. In fact, it was only thanks to the dedicated nursing of this girl - he refers to the beautiful young woman next to him – Crystal of the legendary Inhumans, that he is able to stand at all. He explains what happened.
Flashback narrated by Quicksilver:
He had run into the Sentinels’ Australian base to rescue Wanda but failed. In eluding a Sentinel guard, he ran into a solid wall at full speed and broke like the marionettes their father used to make.
He lay there near death when he saw an unearthly glow. What he saw in his delirium was the Inhumans’ teleporting dog Lockjaw and his mistress, Crystal. The dog’s teleportation had brought them accidentally or providentially to where Quicksilver was. They brought him to the Inhumans’ Great Refuge, where Crystal cared for him. Pietro grew dependent on her, and simultaneously he filled a void that had existed in her life since she had become separated from another.
Quicksilver announces that he and Crystal are in love and plan to marry. Overjoyed, Wanda reveals in turn that she and the Vision are now in love and a couple.
However, her brother reacts unexpectedly and reminds her of his repeated warnings regarding such a travesty. How can he talk like that? she asks. Cannot even his happiness allow him to share hers? What has happiness got to do with their situation? he demands. There is a right and there is a wrong! No sister of his may become involved with a – a robot!
Angrily, Wanda snaps Vision is more human than Pietro. Quicksilver refuses to discuss this any further. He is the head of their family and forbids her to love this thing. Call him back when she comes back to her senses. He will not call her. The screen goes black.
A crying Wanda sinks into Vision’s arms. Captain America grimly thinks if even Quicksilver, who lived with under one roof with the Vision, refuses to accept their relationship, how will the outside world hurt them?
They turn to more pragmatic considerations, namely their low membership ever since Hawkeye quit. They could have used Quicksilver. The Black Panther feels guilty, as his nation has asked him to return home to resume his princely duties.
Suddenly, the communications screen activates but, instead of Quicksilver, they see an aerial view of a mansion. The camera zooms in and through the front door like some Roger Corman film, Iron Man observes. If Vincent Price shows up…
The inside of the mansion is wrecked. The camera stops on the image of an injured bald man lying in the wreckage. The Avengers recognize him but don’t recall his name. The man looks up and asks if the person behind the camera has come back to gloat. He’ll get no satisfaction from him. He may yet destroy his students, destroy him, but no power on Earth can make him the whipped dog he wants to see!
The screen clicks back to black.
Thor recalls the man is Professor Xavier of the X-Men. He swings his hammer, announcing the X-Men need their help or vengeance! He, Iron Man and Vision fly out to search the city for the mansion. Captain America and the Scarlet Witch do the same with the Quinjet and the Black Panther with his one-man-skycraft.
Wanda admits she feels distracted. Cap advises her that the idea of choosing between two loves is Pietro’s. If she were to lose her brother to gain the Vision, it would be Pietro’s choice, not hers. She doesn’t have to play by his rules.
Thor recalls how he once loved the mortal woman Jane Foster and earned the All-Father’s enmity for that. He and Jane persevered, pushing aside all obstacles to their love and in the end their passion died anyway. A most unpleasant parallel to ponder.
Iron Man muses about the many women he’s loved but he’s never seen love like Wanda and the Vision’s. Maybe that’s because Vision’s feelings are encased in plastic and his in iron.
In the meantime in San Francisco:
Hawkeye has reached the Black Widow’s new place and knocks, only to find her recovering partner Ivan at home. Ivan brusquely tells him Natasha is out with Daredevil and he’ll inform her Hawkeye was here. Hawkeye swings up a tree deciding to wait in her arbor until Natasha returns.
Back in New York:
Cap and Wanda have found the X-Men’s mansion and call in the others. Iron Man marvels the place, which puts Tony Stark’s townhouse to shame. They enter and find the insides wrecked. Soon they stumble on the deeply unconscious Cyclops, Marvel Girl and Iceman.
As they find Xavier in another room in the same state, Wanda declares they need to get them to a hospital. She owes the X-Men more than she can ever repay for the kindness they showed her and Pietro when they were forced to work for Magneto.
She and Cap try to get to Xavier when the door slams shut behind them. Suddenly, Cerebro comes to life and attacks Cap. He orders Wanda to get Xavier out while he fights the device with his shield and his new super strength. However, despite his throw, the device still attacks.
Impatiently, he asks Wanda why she is still there. She replies the door won’t budge. He crashes through it. They carry the X-Men out and Iron Man has also found the Angel.
Once they are outside, boulders burst forth from the ground. Vision protects Wanda and Marvel Girl, Iron Man protects the Panther and the other X-Men while Thor transports Cap and Xavier.
Once they reach the Quinjet, the barrage stops. Wanda announces she is certain this is Magneto who is taunting them with his powers. Thor muses that could be true. However, when they battled the Beast-Brood, they found no sign of Magneto, the Panther points out.
Suddenly, they hear an eerie flute melody. And without any warning, several dinosaurs under the spell of that tune rush toward the Avengers. Thor attacks the Tyrannosaurus rex, which chomps down on his leg. Iron Man takes on a smaller one and Cap tosses his shield at a Pterodactyl.
Vision points south at a man who sits there cross-legged playing his flute. He studied Magneto’s allies and Piper was the only one missing. When a Triceratops attacks, he turns intangible and then tangible within the beast. The dinosaurs are beaten but the Piper hasn’t stirred.
When the Avengers walk toward him once again, more boulders stir up and form a protective dome around the Piper. Thor tries to shatter it but some rocks hurl themselves at him.
Suddenly, they hear a mocking voice and find Magneto himself standing behind them, in Angel’s uniform. He explains that, thanks to the uniform and fake wings, Iron Man brought him aboard their ship. He wants the mutants they have carried here along with this fair child of the atom. He grabs Wanda’s arm.
When Cap protests, Magneto hurls Iron Man into him. Attacking the other three Avengers with iron boulders, he flees aboard the Quinjet with the Scarlet Witch, the X-Men and the unconscious Cap and Iron Man. Aboard, he boast his new power is to control minds and the Scarlet Witch’s eyes go blank.
The other Avengers free themselves to find their friends and the plane gone. They swear vengeance but Panther sorrowfully points out there’s only the three of them. Perhaps the old saying is true: divided they fall.