Synopsis
Captain Marvel and Rick Jones used to be doomed to exist 1 in the real universe and the other in the Negative Zone, with only the ability to swap places. But in #39 they learned how to split and merge at will in the real universe. In #40 the Kree Supreme Intelligence claimed that everything that happened to them since Mar-Vell was 1st sent to Earth (Marvel Super-Heroes #12) was orchestrated by him to get them to this story arc. He needs to absorb Rick Jones' latent mental powers (which ended the Kree-Skrull War in Avengers #97) in order to break the Kree's evolutionary stasis (as described back then). The Supremor then granted Rick a share of Mar-Vell's powers, and sent them both on a galactic odyssey.
In #42 they got involved with some asteroid miners and the Stranger, and Rick got himself a costume and a girlfriend only he could see. In #43 Supremor nudged Drax The Destroyer into their path, who was hunting for Thanos (who returned in Warlock #9) and who still bore a grudge for Mar-Vell 'killing' his predestined target the 1st time (CM#33). And Rick learned the ghost-girl's name is Fawn. Last issue CM defeated Drax but in doing so drained power from Rick, almost killing him. Fawn made Drax go away by telling him where Thanos is (and he'll follow the trail to W#15). CM took Rick to Deneb-IV for medical aid but found it overrun by giant robot heads called Null-Trons, ancient Kree weapons who were destroying all life. The duo were captured by an armoured resistance group and taken to their leader, a Null-Tron controlled by a humanoid head on top. The leader told Mar-Vell that his and Rick's minds are merging into 1, but he can cure them.
The General explains that the surviving inhabitants of this world have become cyborgs, now almost completely machine, during their long war against the Null-Trons. Mar-Vell agrees to do whatever the leader says to save Rick.
The general tells him of the properties of the large crimson sphere in front of them which he claims to be 1 of 6 Soul Gems, all of which have different powers but all can affect minds. 1 is in the possession of Adam Warlock, he doesn't know where the other 4 are. The cyborgs take comatose Rick from his life-support chamber and push him into the Gem, and CM follows.
The inside is much bigger than the outside and Rick and Mar-Vell appear separated by a transparent barrier which CM thinks is RJ's 'madness' keeping him away. He tries to break through but Rick interprets this as an attack. He thinks Mar-Vell wants to kill him and decides to fight back.
Out in the world the cyborgs and the Null-Trons clash, echoing the duo's words. 1 of the cyborgs named Rambu has stayed with the General. Rambu removes his helmet and we see he is of the alien race we know as the Aakon. It turns out it was he who stumbled on the Soul Gem (in a 1-panel cameo in #41). And it seems the Gem is using the energy of our heroes' conflict to reinvigorate the war. But there seems to be some ambiguity in what the General deems a desirable outcome.
On the Kree homeworld Hala the Supreme Intelligence gloats to his minion Bun-Dall that he arranged for Rambu to find the Gem as part of his overall manipulation of Captain Marvel's fate. He also increased the ferocity of the Null-Trons (they were originally designed to kill opponents of the Kree, not wipe out all life on a planet). Bun-Dall is worried that 1 of CM or RJ might kill the other. The Supremor says he doesn't need them both, either 1 will do (presumably because of the mind-merging). Bun-Dall still thinks his boss isn't as in control as he thinks.
The General confirms to Rambu that the outcome of the war will be determined by which of CM/RJ wins. But he reveals that he doesn't care *which* side wins as long as war is replaced by peace. And that is because he is an Aakon merged with a Null-Tron. Rambu is understandably miffed.
Within the Gem the 2 heroes break through the barrier between them, and their minds get closer. Each realises that the other could win control of both bodies, and each is determined not to lose. Mar-Vell sends a large monster against Rick, who defeats it by stealing power from *him*. And outside the battle gets more ferocious. But suddenly both sides pause as our duo do too. Both CM and Rick have realised that their fight can only harm them.
Outside the General expects the fighting to soon resume. But Rambu starts to pound on the Gem with his cyborg fists, which causes debris inside to batter the heroes. And outside the Null-Trons and the cyborg army fall over in response. But then Fawn appears and persuades Rambu to take *her* into the Gem, over the General's objections. (Is Mar-Vell the only person who *can't* see her?!)
Our pals struggle towards each other as the substance of the Gem holds them back, and Rick at least realises that they themselves are causing the obstruction. Rambu and Fawn arrive just as the heroes finally clash. Fawn knows that their fight to avoid merging is actually causing the merger. The result could be death for 1 or both, and she says if Rick dies then so will she. Her mesmerising affect on Rambu means that he separates the combatants to save *her*.
Now she is visible to Mar-Vell as well. She persuades him and Rick that fighting each other is the wrong solution. They can take control of their powers and *stop* themselves from merging. And they see the light.
And then Fawn leads the 3 men out of the Gem.