X-MEN: Sanctuary By Christopher Golden, is the second book in the Mutant Empire trilogy, picks up exactly where the first one left off, and develops the story further toward the resolution in the last novel.
Just as with Siege, Sanctuary keeps the X-Men team divided into two halves, with one half dealing with a crisis in space while the other half begins to fight Magneto's takeover of New York down on Earth.
I should mention right off that this novel's development is a little slower concerning the "away" (space) X-Men team. It should be noted that they came a long way in Siege - they traipsed halfway across the galaxy to another planet, fought through a legion of alien soldiers to rescue two prisoners, fought their way back out to teleport home, and then were stranded in a dead ship. But Sanctuary spends the WHOLE novel detailing this team's attempts to get home in a poor attempt at stalling. In essence, this team remains in space for the whole novel, and this subplot overstays its welcome.
Meanwhile, back on Earth, Magneto's new empire in New York City is slowly growing. The other half of the X-Men fly in to infiltrate it and fight the entire city. They run into many familiar villains, from the Marauders to the Brotherhood of Evil Mutants, before charging Magneto head-on in the Empire State Building.
Where the space subplot fades out, another one comes in. This one deals with Charles Xavier's attempts to deal with the political crisis. He does some spin-doctoring on the major news networks, but the major conflict in this subplot is the test of his ethics. Will he violate his code of honor and use his telepathic powers to avert the greatest crisis and setback in the struggle for mutant rights and acceptance? The answer will surprise both old and new readers - I was totally floored.
And Golden develops yet another layer - the rivalry between Valerie Cooper and Henry Peter Gyrich, which previously merited only a few pages, now takes a level of importance in Sanctuary. Cooper wants a relatively clean end to this crisis, but Gyrich naturally obstructs her plan and proceeds to set up an assassination attempt called Operation: Carthage (and before it happens, you KNOW it will make Bay of Pigs look like a cakewalk). I also liked the portrayal of Gyrich as a slightly deranged bigot, as his reasons for hating mutants come to light and expose a very twisted mind.
All in all, where Siege was the exposition, Sanctuary obviously serves as the buildup to the climax. While parts of the novel seem like pointless filler material, Golden still continues his masterful pacing and excellent characterization toward what will be one amazing finale.