After House of M we jump right back into Claremont's Great Run
Welcome back to Uncanny X-Men: The New Age. I do hope that you did read the House of M books because they explain a lot about what's going on here. (Especially the side plot with Wolverine and Storm) But if you didn't want to, I'll do a quick recap - something happened to Scarlett Witch. I don't read Avengers so I can only go on what was given during the House of M book. Apparently she lost her pregnancy and went crazy and killed a bunch of Avengers. Xavier's been trying to keep her sane because, like Franklin Richards of the Future Foundation/Fantastic Four-extended family, it's dangerous to have reality altering mutants who are mentally unstable. Unfortunately, Prof X's plans aren't working. He call the X-Men and Avengers together to figure out what to do. If he can't contain her (and he's one of the most powerful telepaths in the Marvel 616 Universe), what choice do they have? Unfortunately, hot-tempered Quicksilver concludes this means they're goimg to kill her and goes back to Genosha to tell his father and sister. I think the excellent writing leaves it up to the reader to figure out if they were going to do that. Sure, someone suggests it, but Captain America vetoes that and I'm not entirely convince they would have done it. Perhaps Reed could have put her in the Negative Zone or something..... we don't get to find out because Quicksilver convinces her to change reality so that mutants are the dominant people and everyone wishes they were mutants and it's the humans who are discriminated against.
Eventually things are set right, but Scarlett Witch utters the words "no more mutants" which, for some reason, leaves 198 of them untouched. I didn't get ALL of the House of M books, so I don't know the exact situation that leads to the Sentinel O*N*E squad guarding the mansion, but I think you'll want to read Son of M (with Quicksilver's machinations after having lost his powers) to understand that as wella as the main antagonists of this book. So, onto the book:
As I mentioned above, the X-Men feel trapped in their own "sanctuary" by the sentinels. I think Claremont does a good job here with the way government double-speak works. On the one hand, the Sentinels are there to keep humanity, who's pissed at the fact that M-Day happened (although I'm not 100% sure why because they shouldn't remember it - just some of the people involved do) from harming the mutants. At the same time, they're there to keep the mutants in. Just like everything that's happened since 11 Sept 2001 with different measures the government has taken, you can laugh with the laughter of near-insanity as they explain that they can't protect the X-Men if they're off on their own, therefore, they need to stay "protected" at the mansion. It's not a prison, it's for protection. (This situation leads directly - if not by way of the next and final book of the Claremeont run - to the situation in Civil War: X-Men)
The book opens up summarizing part of this as well as containing some Pylocke fan service although it's definitely tolerable because it has a purpose. See, these new Sentinels have humans pilots as the machine-only sentinels were too easy to outwit. So Psylocke is purposely trying to titilate them.
As far as the main story goes, Claremont continues last book's focusing on Rachel Grey (Marvel Girl) as the book's main character. She goes to visit her grandparents - Jean Grey's parents. From what I understand, the universe she comes from is just like ours up to a certain point, so it's not like the Nightcrawler daughter mentioned in the previous book. She is Scott and Jean's kid - just not from our universe. Unfortunately, the Shi'ar believe that the Phoenix has a tendency to favor the Greys and so have come to eliminate the Greys. (Hence the title) The same X-Men B-team that has been the focus of Claremont's run has focused on come to attempt a rescue.
The rest of the book focuses on Rachel dealing with what happened at her grandparents' house as well as the X-Men in general dealing with the Sentinels keeping them imprisoned. There's also a B-story with Wolverine and Storm (who were away during the imprisonment) dealing with the anti-mutant rage around the world.
Overall, the pace is very different from the previous book. That one was almost completely action-packed. This book, on the other hand, is very reflective. A lot of the X-Men are dealing with their conflicted feelings post-M-day. Also, Bishop is actually cozying up with the Sentinel O*N*E people which comes to a head during the Civil War: X-Men book. Just goes to show that you can always count on Bishop to be a real PITA.
This is another book I recommend because of what it deals with and sets up. You get the X-Men post-M-Day. You get the setup for the Civil War series. You see what's going on with Rachel, who's about to become a huge main character in the current X-Men: Legacy storyline. You get hints at Psylocke and Nightcrawler's blossoming relationship which is important in the current X-Factor storyline. It's expensive to get caught up with all these old books, but they provide great context for what's going on now and are definitely worth acquiring as youo get the chance if, like me, you end up feeling invested in your main characters. Definitely a recommended read!