I’ve read that this story wasn’t intended to exist in continuity—it was just a way to talk about racism using superheroes—but later got folded into continuity.
Magneto goes after Reverend William Stryker, who ordered the murder of his own mutant child. Along the way, Stryker gets one-upped by Professor X in a televised debate and, being a sore loser, uses his Purifier Army (guys in armor) to kidnap the Professor so that Magneto and the X-Men have a reason to team up to save their mentor.
It’s a very well-written tale, but using mutants as a social construct doesn’t cover any new ground. Good character work for Magneto—showing him as more of a militant than a villain—but it’s not like we didn’t already see Claremont doing this in his Uncanny X-Men title. Very nice to see the likes of Brent Anderson on art. Beautiful art, all painted.
It’s also the first time Wolverine popped two claws and threatened to pop the third…
The second X-Men movie, X2, was loosely based on this story.