Basically, this starts off in pre- AvX Uptopia on a deceptively quiet(ish) day, when up pops Storm behaving in a most un-Storm like manner; the next thing Cyclops (Scott Summers) knows he has been whisked off to another of those realities.
This scenario sets the scene for the X-treme volumes in that all is not as cut and dried as it might appear. Yes we have an Xavier as a villain, but not one of those dire pantomime, scenery chewing types (I still groan over one encountered in the Excalibur arcs). In this world, A Brotherhood of Mutants led by a Magneto declared war against Humanity, but a team of X-men led by Xavier defeated him, before Magneto died, he damaged the world to the point of possible destruction; the only way this Xavier can keep this at bay is by kidnapping mutants from various realities and harnessing their powers, however these victims die. His rationale was that some of his original surviving X-men volunteered for this sacrifice. So there is the ethical tension. The Xavier sees this as a price to be paid. He views alternative mutants as an endless source to be used to save his own world. Cyclops and other captives (a James Howlett, A Kurt Wagner (nearing adolescence) an Emma Frost and a Kitty Pride-shadow)of course don't see it that way and thus the struggle is on.
Variations on some familiar themes are played out. The comradeship/hate relationship between James Howlett (or Wolverine) and Scott Summers (Cyclops) seems to be a constant in all universes. Emma is supremely sophisticated and sardonic. Artists seem obsessed with Storm's extreme Mohican hairstyle. Armor has an important role and is heroic as she is in the Marvel 616 or Ultimate world.
The action and the narrative move along without getting in each other's way, and story manages to involve some of the X-men from Marvel 616; the meeting of the two Emmas is of course entertaining. Some of the images are very striking, such a room with a large pile of Cyclops visors, though Scott running about in bare chested mode is not one I personally care for.
This concludes with Scott being reflective and sets the scene for the next run.
There is an additional one issue story set in the Emma's world, a steam-punk place, where the X-men are the X-Society. In addition to Emma, there is a Cyclops, Beast and Wolverine. A sombre tale one which merges favoured steam-punk themes with those familiar to X-men followers, such as suspicion of mutants and sentinels; I would not swear to it, but I think a Cable as well. Told by Emma, this sets up a rationale for her actions in the X-treme X-men arc.
Overall a good addition to anyone's collection of X-men books.