The X-Men face a trial for Magneto and a cosmic threat while grappling with internal strife and external enemies. The Avengers seek to bring Magneto to justice for his past actions, but the X-Men find themselves defending him, creating a rift between the two heroic teams. Simultaneously, an alien force named Horde emerges, posing a threat that requires the X-Men's full attention. As their ranks are decimated and presumed lost, the remaining mutants regroup in Australia, only to become the targets of the ruthless Reavers, forcing them to confront their new reality and fight for survival.

This collection is celebrated for showcasing a pivotal era in X-Men history, particularly the artistic contributions of Marc Silvestri and the narrative depth provided by Chris Claremont. The inclusion of the 'Fall of the Mutants' storyline is frequently highlighted as a transformative event for the characters and their world. Readers often praise the dynamic interplay between the X-Men and the Avengers, as well as the introduction of compelling new threats like Horde and the Reavers. The volume is seen as essential for understanding the evolution of the X-Men during this period, marked by significant character development and high stakes.