Loki, with the assistance of the Other, the leader of an extraterrestrial race known as the Chitauri, starts a plot to subjugate the Earth. That leads Nick Fury, the director of the espionage agency S.H.I.E.L.D., to gather a group of mightiest heroes including Thor, Captain America, Iron Man, Hulk to form a team to prevent Loki from enslaving humanity.