The Marvel Cinematic Universe is the most successful franchise of all time and it has changed the way movies are made. Taking a cue from their comic book source material, these films tell different characters’ stories that all take place in one massive, interwoven universe. Each film would introduce one key protagonist, building toward the release of one giant blockbuster, The Avengers, that would put them all together. If a single one of those films failed at the box office, it could derail what may be the biggest gamble ever taken in the history of cinema. How did Marvel pull it off?