Three team-based Mutant books (Wolverine’s solo comic is left out, as is X-Men) participate in an event focusing on Genosha.
Page one of the first issue of the event shows two lineups of the X-Men teams. The Forge Team, which includes Gambit, Banshee, Jean Grey, and the now-adolescent Storm. And the New Mutants team, led by Cable.
Storm may be a kid, but we’re shown that her powers still work well.
The “regular” X-Men team, which had been in Australia, is recovering from the shattering of the Siege Perilous magic item. But they rejoin the Forge team when the Genoshan Magistrates (led by Cameron Hodge and accompanied by Havok) attack the X-Men due to their interference with Genoshan affairs in the previous story arc.
Hodge is fused with a computer now…
Cameron Hodge, who is just a head on a robot body because Archangel cut his head off his old body, wants to use Warlock’s transmode ability to generate a new, super-body for his severed head.
Short version: It’s basically just the X-members united in a war against the mutating scientists of Genosha.
Typical with Chris Claremont, there’s a lot of recap-scenes with characters talking about their various statuses, and it’s helpful because the X-Men book alone regularly features over a dozen characters—each with their own plotlines—in every issue.
The kids break free, battle Hodge’s warriors, but in the effort Warlock appears to be killed…
…And Wolfsbane is re-captured and turned into an agent of Genosha.
Now it’s just a free-for-all as the rest of the mutants come together and invade Genosha to save their teammates.
There’s a lot of capturing/getting free/recapturing, mutants getting turned into Genoshan mindslaves, etc. By the end, Storm is a grown-up again (I don’t really understand how that happened), Cameron Hodge is unseated as the leader of Genosha, Genoshan scientist Dr. Moreau is killed, Havok is back with the X-folk, and there’s a funeral for Warlock.
Warlock’s ashes are spread on Cypher’s grave site, and there’s already a hint he’s not really dead.
Also, the X-Men team is reformed as Storm, Wolverine, Banshee, Forge, Psylocke, Jubilee, and Gambit.
Yes, I’ve abbreviated a lot, but really the action puts-and-takes aren’t important.