After the Earth falls under attack by a mysterious force, the dangerous and villainous foe by the name of Onslaught was behind all this chaos and he has become too powerful and Professor Charles Xavier calls out for heroes to stop him before he merges with the consciousness of Magneto and become the being known as Onslaught forever, so the Marvel universe is assisted by the Capcom universe and they arrive to save the planet from Onslaught and his apocalyptic scheme then destroy him before he is unstoppable!