Collects Decimation: House of M - The Day After, X-Men (2004) #177-181.

It was the worst day in X-Men history. Now it's the day after. The House of M is over, but the effects will be felt for the rest of their lives. How do the X-Men pick up the pieces in a world that has completely changed? Plus: Something's amiss at the House of Xavier! A sneak attack forces the X-Men to re-evaluate just who their friends are, and to align themselves with former enemies!