Marlon Brando plays the lead of an outlaw biker gang in a movie that basically created the sub-genre of biker gang movies and pioneered a lot of the cliches that are associated with it. It's loosely based on real events, but they get more violent in the film. They go from town to town creating trouble and drinking the bars dry. Then they move onto the next town. There's a rival gang that they fight with. There's a town that wants to start jailing or shooting everyone on a motorcycle.

Marlon Brando is the definition of cool in this role. It was used as inspiration decades later by Elvis and James Dean. I would say a lot of the appeal to this movie is just how cool he looks in a leather jacket. There's some really fun scenes with the gang drunkingly destroying the town, but it's Brando that is most memorable.