The Avengers return to see that in their absence Loki has turned the Earth into a frozen wasteland and plans to use Asgardian World Breaker ships to unleash Ragnarok.
Peggy Carter and Howard Stark find themselves catapulted from the 1940s to the present day, but they don't know how. Captain America and Iron Man are on the case.
After a strange energy field appears in Central Park, the Avengers are transported to a new world where Black Widow and Captain America must find Iron Man and battle the mysterious Moon Knight.
Loki joins the Avengers in their search for the Bifrost and a way to undo Battleworld and repair Earth. They must battle the Enchantress along the way.