Loki, the adopted brother of Thor, teams-up with the Chitauri Army and uses the Tesseract's power to travel from Asgard to Midgard to plot the invasion of Earth and become a king. The director of the agency S.H.I.E.L.D., Nick Fury, sets in motion project Avengers, joining Tony Stark a.k.a. the Iron Man; Steve Rogers, a.k.a. Captain America; Bruce Banner, a.k.a. The Hulk; Thor; Natasha Romanoff, a.k.a. Black Widow; and Clint Barton, a.k.a. Hawkeye, to save the world from the powerful Loki and the alien invasion.
Earth's mightiest heroes must come together and learn to fight as a team if they are going to stop the mischievous Loki and his alien army from enslaving humanity.