In Asgard, Odin muses on Thor being absent from Asgard and his state of mind. Thor meanwhile, being persuaded by the Mind Valkyrie, to raze not only Asgard, but all the Nine Worlds. While Thor rages, Sif and Beta Ray Bill look on, determined to try to talk sense into Thor. Thor strikes Sif down, when Bill appears. Thor easily defeats the both of them. Bill pleads for Sif to leave to gather more allies, or warn Odin if necessary. Sif leaves via the Norn Stones, and Thor strikes Bill with enough force to shatter the asteroid they were fighting upon. Before Thor can deliver the killing stroke though, the Silver Surfer arrives.
The Silver Surfer is passing by, and happens to notice Thor about to kill Beta Ray Bill. Surfer manages to intervene, and then he and Thor begin to battle, giving Bill time to recover and join in. During the battle, Thor speaks to the Mind Valkyrie and draws strength from her, enough to incapacitate Bill. The Surfer sends his board to carry Bill away from the battle, where he is intercepted by Sif, who takes them both to Asgard. Thor manages to smash the Surfer, sending him plummeting to the planetoid below them. But when he arrives there to finish the job, Thor finds Pip the troll and Adam Warlock waiting for him.
Moondragon is using her mind gem to probe Maxam's thoughts trying to break through his amnesia without success. Warlock goes to probe his Orb of Eternity, and observes Thor and notices something is not right, with a flash of his soul gem, he now sees the Mind Valkyrie with Thor. Eternity appears and they discuss Adam's method of making people with great power indebted to him. Eternity suggests that if Warlock could cure Thor, he would be eternally grateful. Adam summons Pip, and they go to confront Thor, arriving just before Thor is about to kill the Silver Surfer.
Warlock and Pip arrive just before Thor is about to kill the Silver Surfer, Pip jumps out, but Adam says that he understands Thor lashing out. He does not understand, though, why Thor would turn to the Mind Valkyrie, one who does not exist. The Mind Valkyrie prods Thor to kill Warlock as well. As they engage in battle, the Surfer comes around and they both begin to attack Thor. Meanwhile, in Count Abyss' dimension, he gains something that will help him steal Adam Warlock's soul gem. Adam tries to subdue Thor with a karmic blast from his soul gem, but it has no effect on Thor at all. Thor proceeds to beat the living hell out of both Warlock and the Surfer, when the Surfer's board slams into Thor from behind and begins to carry off both the Surfer and Warlock. A little off, the Surfer comes around and realizes that Adam is controlling the board, a feat he is now capable of since they once shared souls. Warlock states that Thor is still insane and they must try once again to stop him.
On Monster Isle, Pip is trying to convince the rest of the Infinity Watch that they should go rescue Adam Warlock from being pummeled by Thor. When Pip tells Drax about "Longhair", he forces Pip to transport them to Thor. While Adam Warlock and the Silver Surfer go off to find allies against Thor, the rest of the Watch appear and Drax immediately starts pounding on Thor. Moondragon tries to use her mind gem to free Thor from his madness, and winds up giving the Mind Valkyrie a life of her own, apart from Thor's shattered psyche. She and Thor then begin attacking the Watch with renewed vigor. During the battle, Drax loses his power gem, which Thor now claims. When Pip notices this, he immediately teleports the Watch away to find Adam.
Adam Warlock and the Silver Surfer are on Earth, looking for the aid of Doctor Strange. They go inside his house without being invited and become lost inside. Strange arrives and they tell him about Thor going mad. The rest of the Watch arrive and tell them about how they showed up and lost the power gem to Thor, and causing the Mind Valkyrie to take on a life of her own. Meanwhile, in Asgard, Sif tends to Beta Ray Bill's wounds. The Watch and the rest of the heroes are off to Asgard to try to stop Thor.
The group of heroes arrive in Asgard, and are intent on warning Odin that Thor has gone insane. Beta Ray Bill and Sif watch on via the mystic Norn stones, and determine that Odin must not find out about Thor's condition. In the city of Asgard, Odin senses that something is amiss. While Beta Ray Bill delays the group of heroes, Sif prods a group of trolls under command of Geirrodur to attack her. She leads them towards the heroes, then she and Bill depart via the Norn stones. The heroes put of a good fight, but eventually they are all defeated. Geirrodur calls for them to be mystically bound and prepared for the sacred sacrifice.
In Castle Grimlock, the home of Geirrodur, he and his Troll Witch look upon their captives and discuss their sacrifice to Borgeddon. When they come to Pip, they discover that he has troll blood in him, so he is accorded certain rights. He shall face ritual combat, if he wins he goes free while the others die, if he loses they all die. He agrees to the combat, but is allowed a substitute, and he chooses Adam Warlock. Adam goes into the arena and faces off against Olik, the older brother of Ulik. Adam proceeds to fight rings around the huge troll, meanwhile, Pip frees the rest of the heroes. Adam quickly disposes of Olik, the heroes crash their way out of the castle.
Thor and the Mind Valkyrie arrive in Nidgar Keep, before continuing on to the city of Asgard. The rest of the heroes arrive and try to stop Thor once again. Elsewhere, Sif and Beta Ray Bill decide to use the Norn stones to travel to Thor's side, once more in an attempt to stop him as well. Thor and the Mind Valkyrie easily dispatch the heroes, when Sif and Bill arrive. Pip and the Surfer fly towards Thor and the Mind Valkyrie and Pip teleports them to the sanctuary of Thanos, who is none too happy to have unexpected visitors.
Having transported himself, Thor, Silver Surfer, and Mind Valkyrie to Thanos' ship, Pip hides out on a balcony and watches the raging battle between Thanos and Thor and between Mind Valkyrie and Silver Surfer. Thor and Thanos go toe to toe for a while, with Thanos apparently enjoying the conflict for a while. Surfer manages to defeat the Valkyrie, when Thanos simply turns around and leaves the room. Thor thinks that he is running from him, but Thanos returns with a gun, and uses it to encase Thor in a stasis field. Just then, the rest of the heroes appear, when Thanos tells them that the field will not hold Thor for long, and if they are going to cure him, the should do so quickly because as soon as he is free, Thor will undoubtedly destroy them all.
Thanos and the heroes attempt to merge the Mind Valkyrie back into Thor's psyche. In Asgard, Sif and Bill arrive at Volstagg's home and ask him if anyone has seen Thor, and he states that no one has seen him since he left Asgard. Sif and Bill still want to try to cure Thor without Odin knowing about his condition. During the procedure to merge Thor and the Mind Valkyrie back together, the heroes are swept into a psychic plane of existence, only to have the tables turned on them and they are swept into Thor's madness. They use force of will and manage to escape. The Mind Valkyrie disappears, apparently dissipated, and Thanos' machinery explodes. They have about 2 hours before Thor escapes. So they decide that no matter the consequences, they must take Thor to Odin.
Thanos and the heroes arrive on Bifrost and take out Heimdall. Odin senses this attack, and unleashes all of Asgard's warriors to attack them, thinking that the imprisoned Thor is to be used as some sort of bargaining chip against Asgard. The heroes manage to turn the tide against the Asgardians, so Odin himself enters the battle. Thanos takes on Odin one-on-one and gives as good as he gets. But soon Thanos goes down, and before Odin can deliver the killing stroke, Sif and Bill appear and stop him, telling Odin about Thor's madness. They determine that it is not Warrior's Madness which Thor suffers from, since it comes from Odin's past manipulations of Thor's spirit. Odin tries to cure Thor, but fails. And since Thor possesses the power gem, he would destroy everything unless is he killed, and Odin decides to do just that.
Odin determines that Thor must die to save everything else. Doctor Strange and Adam Warlock stop him, telling him that he tries to pound the insanity out of Thor, when it should be cut away, like a surgeon. Odin agrees and re-enters Thor's psyche. Inside, Odin finds a gigantic mountain, which he climbs, and at the top, he finds Thor in chains. Thor tells Odin that he has been there for a long time, and cannot free himself because he is so weak. Odin tells him that he himself is to blame since he forged the chains out of his own righteousness. Odin breaks the chains, but before they can leave the Mind Valkyrie shows up. Odin and the Mind Valkyrie begin to fight for Thor, as she wants to return to the life that she was given by the mind gem. She tells them both that if she is destroyed, they will destroy Thor's mind as well. Thor takes the risk and destroys her. Thor and Odin and transported back to Asgard, and Thor's mind is clear now. He thanks everyone, even Thanos, that helped in his cure. The Mighty Thor has returned. But in a cave, someplace dark, we see Loki bound in chains, declaring that he will not be a prisoner forever.