Marvel's Avengers begins at A-Day, where Captain America, Iron Man, the Hulk, Black Widow, and Thor are unveiling a high-tech Avengers Headquarters in San Francisco - including the reveal of their own helicarrier powered by an experimental energy source. The celebration turns deadly when a catastrophic accident results in massive devastation. Blamed for the tragedy, the Avengers disband. Five years later, with all super heroes outlawed and the world in peril, the only hope is to reassemble Earth's Mightiest Heroes.
—Crystal Dynamics and Eidos Montreal