Synopsis
The Apocalypse Twins' plot has succeeded. The Earth has been destroyed so that their hated 'father' Kang can't rule it. Eimin the surviving Twin has saved all mutants by taking them to Planet X. 6 years later the surviving Unity Squad members Havok and Wasp (the only non-mutant on the planet) with help from Beast have brought Kang and his cross-reality super-squad to prevent it all from having happened. But some mutants led by Magneto have interrupted them.
Magneto is trying to get Havok to tell him his plan. But Cyclops fears that Erik's interrogation methods may kill his brother. Meanwhile Psylocke, another member of the ruling X-Council, fights the alternate future version of herself Magistrate Braddock. Our Betsy wins the duel of psi-blades. Cable doesn't do so well against his future clone Stryfe.
Wasp is lying comatose after last issue and Beast protects her from Magneto's X-Force. He stops Blob and Pyro, but Lady Avalanche wraps him in stone. Blob grabs Wasp by the throat and threatens to kill her. Magneto similarly magnetically squeezes Alex Summers harder.
But Cyclops can't stand any more and knocks Magneto down with an optic blast. He offers to support Alex's plan if Kang can really do what the X-Council thought was impossible - save the Earth. Havok points out that villain Kang has an ulterior motive to succeed - he wants a future Earth to rule.
Alex is also honest enough to admit that Kang has his and Jan's daughter Katie hostage. And that resetting history will erase the current version of the future. (He doesn't mention that Katie will be saved from this fate.) Scott agrees to help.
Elsewhere in Eimin's 'throne' room Thor is attacking the Apocalypse Twin with Mjolnir and Jarnbjorn - the axe that he enchanted to be capable of killing Celestials, and that the Twins used to do so, dooming the Earth. Meanwhile the Earth X Venom captures Daken (resurrected by Eimin to be 1 of her 4 Horsemen).
Kang stops Thor from killing Eimin - their goal here is to free Unity Squadders Sunfire and Wolverine from their stasis/torture prisons. Left with his 'daughter' Kang claims that the Twins' 'rebellion' was all part of his plan.
Daken breaks free of Spider-Girl/Venom's web and tries to kill Kang. But his released father Wolverine stops him. Logan brutally assaults his son but stops short of killing him again. (Although he still claims it was the right thing to do last time.)
Sunfire takes out his 6 years of agony on Banshee (the other surviving Horseman). They were once friends but Sean let Shiro suffer. Cassidy blames it on his transformation into a Horseman. Logan stops Shiro, reminding him that they've both been through that too. (Meanwhile the Abomination Deathlok and Iron Man 2020 have just been standing around.) Kang leads his expanded group away.
Back in the other place, Doom 2099 saves Wasp by blasting Blob. But Magneto revives and magnetically floats Doom, Wasp, Stryfe and Ahab in the air. But Cyclops optic blasts him and Havok cosmic blasts X-Force. The X-Council members Cable, Psylocke and Storm (who's been conspicuously absent so far this issue) back Scott. Havok and Beast take Wasp away with the Kang squad, leaving the X-Council facing X-Force.
Kang is discussing his plan to reset time. Wolverine agrees as long as they pick a time before Rogue died (#14). If she doesn't live then he'll see the Earth destroyed rather than let Kang have it.
The other lot arrive with a revived Wasp, who proceeds to beat up Kang. She wants daughter Katie back. But Kang reminds her that keeping Katie in the slipstream is the only way to save her from disappearing with the rest of this timeline. Sunfire is very unhappy about trusting Kang, but Wolverine knocks him out (for his own good).
Thor claims that this disaster is his fault for empowering Jarnbjorn (#6). But the Unity Squad was also to blame for splitting into 2 factions (#9). (Described here as mutants vs humans, but it wasn't actually like that.) Now Kang's plan is to send the available members of Unity Squad mentally back in time to occupy their own bodies, and use their knowledge of this future to prevent it from happening.
Magistrate Braddock links the minds of Havok, Sunfire, Thor, Wasp and Wolverine. With the help of Doom 2099, Iron Man 2020 and Kang their consciousnesses flee their bodies. Beast, Kang and his team are left to see the world dissolving.