Synopsis
The splash page reminds us that years ago Thanos gathered together the 6 powerful Infinity Gems to try to kill half the universe. After his defeat cosmic forces stopped the Gems working together, and scattered them throughout the universe.
Mr Fantastic has convened a meeting with the rest of the Illuminati (Black Bolt, Dr Strange, Iron Man, Prof X and Sub-Mariner). He shows them the red Power Gem, which She-Hulk gave him after taking it from Titania. Reed reminds them how often the Infinity Gems have been united to cause major problems. They dismiss the idea that the Gems can no longer be used together (mainly I would presume because they've seen them combined since that prohibition was made).
Reed Richards proposes that they seek out the Gems themselves before someone else does. He then reveals that he has the Infinity Gauntlet to hold them, and has in fact already retrieved 2 more of the Gems (the green Soul Gem and the purple Space Gem). He says he's discovered that the Gems talk to each other, and he can use them to find each other. But as he increased the number of Gems he had they became more difficult to control. Which is why he's brought them to the Illuminati.
Mr Fantastic causes the Gauntlet to show them the locations of the other Gems in a sort of virtual reality. The blue Mind Gem is in the universal collective unconscious, the yellow Reality Gem at the edge of reality, and the Time Gem is adrift in time. He proposes they split into 2 teams to get the 1st 2 Gems. Then the combined might of the 5 Gems should be enough to bring the Time Gem to join them.
Dr Strange, Prof X and Sub-Mariner go after the Mind Gem. Charles Xavier uses Cerebro at the X-Men's school to help him send their psychic projections into the unconscious of the universe. Dr Strange's astral form should be able to bring them back. Namor is there as muscle. They find that the Mind Gem isn't just in the collective unconscious, it is the universal unconscious.
They imagine themselves standing on an infinite blue crystal plane. But Namor also thinks of it as an ocean, and a giant fish surges up to attack them. Sub-Mariner saves Prof X. He claims that since the fish obviously came from his imagination, then it's up to him to defeat it. But actually a spell from Dr Strange helps as well.
In the Baxter Building Reed and Tony Stark use the power of Black Bolt's voice to open a hole in reality. Iron Man expresses surprise at what he senses through the rip, but we're never told what it is. Instead he just reaches in and pulls out the Reality Gem.
Of course it's not as easy as that, and the Gem starts to erode him away, and the floor he drops it on. A gesture from Black Bolt suggests Mr Fantastic use the gauntlet and its 3 Gems to take control of the new Gem. Driven by worry for Human Torch and Thing who are also in the building, Reed grabs the Reality Gem with the Gauntlet and struggles to master it, eventually restoring Iron Man back to existence.
The other 3 Illuminati return with the Mind Gem. Reed adds it to the Gauntlet, and the 5 Gems summon the Time Gem to them without his intervention.
Mr Fantastic seems lost in the power (literally) at his fingertips. He ignores the others' entreaties and threats to take the Gauntlet off. Uatu the Watcher even drops in to talk Richards down. But when Reed comes to, he explains that he'd tried to use the Gauntlet and Gems to wish themselves out of existence. But he couldn't make it happen.
Richards then offers the Gauntlet to the Watcher. But Uatu says no one being should have all the Gems. Reed suggests that each of the Illuminati take a Gem and hide it, even from the others. Watcher still isn't too happy, but is willing to let it be.