When the heroes and villains of the Marvel and Capcom universes are thrown together, their two worlds collide in catastrophe. Seeking their own twisted vision of order, the demon lord Jedah and the embodiment of Death set a scheme in motion around the fabled Infinity Stones. In the chaos, the machine intelligence Ultron and the ruthless Sigma seize the Space and Reality Stones, fuse their dimensions into one, and merge into a single terrifying being called Ultron Sigma. To wipe out all organic life, they unleash an evolving virus that converts living creatures into synthetic servants under their control. Facing extinction, an unlikely alliance of champions from both worlds bands together, striking a wary bargain with the mad titan Thanos to hunt down the remaining Infinity Stones. From the halls of Avengers Tower to distant kingdoms and space stations, these legendary warriors must set old rivalries aside to reclaim their merged world.