Iceman has gone missing and the rest of the X-Men are following his ice trail into the swamp. It is not long before they encounter the Man-Thing. Assuming that the Man-Thing had captured Iceman, the X-Men start attacking it. Any contact made with the creature draws them into its body.
Events flashback to yesterday, when the X-Men had “the entity that played havoc with [their] powers” sent back into space. It was at the Kennedy Space Centre that a “strange energy reading” was detected during the space launch. Xavier decided to investigate it, and paid a visit to Dr Conners, who lived in that area.
Xavier suspects that the extraterrestrial’s “strange properties triggered another phenomenon in this area”, but there is interference blocking Xavier’s mental scan. The X-Men proceed into the swamp on Dr Conners’ hydrofoil, to give Xavier a wider scanning range.
Moving into the fog, the X-Men run into weird situations, such an encounter with a Nazi World War II submarine from the 1940s, mythical warriors on pegasus, and a fire-breathing sea dragon. As quickly as they appear, they vanish into the fog. Iceman, trying to evade the sea dragon, vanishes into the fog as well.
Xavier finally regains contact with his X-Men. A strange projection appears to the X-Men, as well as Xavier. Dr Conners recognises it as the mythical Man-Thing. Xavier is unable to read it’s mind.
Suddenly, Marvel Girl and Beast are sucked into a portal that opens up above them. Xavier stops Angel and Cyclops from going after them. They are then attacked by a wild animal. Xavier gains mind-control of Man-Thing and stops the wild animal from attacking Angel and Cyclops, and they step into the portal. The wild animal turned out to be Beast, and beyond the portal, they had stepped into an alternate reality that distorts their powers. Man-Thing “has a special connection to the Nexus” and is able to navigate through the swamp, unaffected. Connecting his mind with Man-Thing, Xavier is able to locate Beast and pull him back into their reality.
With the help of Man-Thing, they are also able to find Marvel Girl and Iceman in their alternate realities. Cyclops, Angel and Beast find Marvel Girl has become Dark Phoenix. Blinded by rage due to Cyclops’ death in this reality, Dark Phoenix has destroyed the entire world. Cyclops, as well as Xavier inside Man-Thing, are able to connect with Dark Phoenix and pull Marvel Girl out of this alternate reality.
Finally, they find Iceman’s alternate reality where he has turned into the “Ice Giant”, and in battle with Thor. Xavier pulls Iceman out of the Ice Giant and back into their reality. Having guided the X-Men back to safety, Man-Thing disappears into the swamp.
Xavier learns that Man-Thing was once human, who’s scientific experiments transformed him into the creature of the swamp. Passing through the portals, the X-Men’s fears manifested into their worst nightmares. The Man-Thing sensed their fears and came to their aid.