The Phoenix Force is on a destructive path towards Earth, with Hope Summers, daughter of Cable, as it's next potential host. The X-Men and the Avengers are divided on how to handle the situation. The X-Men believe that the Phoenix Force will herald the rebirth of the Mutant Species, while the Avengers believe that it will bring an end to all life on Earth. This leads to a war between the two powerful superhero factions.

The fight began after Nova (Sam Alexander), fell to Earth and crashed in New York after an encounter with the Phoenix Force. He manages to whisper a warning to the Avengers before fainting. Meanwhile, on Utopia, Scott Summers trains his granddaughter, Hope, and pushes her to her limit, which in turn makes her summon a fraction of the Phoenix Force. Seeing this, the X-Men believe that this means the rebirth of Mutantkind as they know it, and some people begin hailing Hope as the "Mutant Messiah". However, the Avengers believe that should the Phoenix Force arrive, it would mean death and destruction for all of Earth's people. So, Captain America leads his team to the Mutant Island of Utopia, and pleads his case. However, the X-Men disagree, which leads to a heated battle that kick-starts the entire confrontation. Now, the Avengers and the X-Men are battling globally, from Latveria, to The Savage Land, to Tabula Rasa, to Wakanda, to Wundagore Mountain. Various news reports gave good coverage of the fight, with many civilians cheering for either side, but not knowing the full story. Now, you were also caught in the middle of the conflict. Which side will you choose?