Clint Eastwood stars as Jed Cooper, a former St. Louis lawman accused a being a rustler in Oklahoma & Indian Territory 1889, not 1873 as the liner notes erroneously state. He is set upon by a posse filled with questionable characters and hanged before the opening credits. Lucky for Cooper, Federal Marshal Dave Bliss (Ben Johnson) comes along soon after and cuts him down. He is then placed into a paddy wagon and taken before Judge Adam Fenton (Pat Hingle), who finds Cooper's story checks out.
Cooper wants revenge against the nine men who hung him, but Fenton tells him he can't take the law into his own hands. Instead, he offers him a job as a marshal on the condition that he brings the men in alive. Suffice it to say, Cooper hopes they give him a reason not to, but he agrees. While working as a marshal, Cooper questions Fenton's rigid administration of the law, but the judge says it's required to keep people from acting as vigilantes and to earn the territory statehood.
After a few of Cooper's assailants are apprehended, those remaining offer him a bribe. He takes the money because it's what he's owed for the cattle he lost, but things ain't square as far as he's concerned and he plans on finishing the job he started.
Hang 'Em High is a very good western that provides plenty of action while also offering food for thought about justice. There's a subplot about a young woman Rachel (Inger Stevens) who is obsessed with looking for her husband's killers. She becomes entwined with Cooper, and while the parallel is evident her character doesn't add much to the story. It's great to see a lot of familiar faces in small roles, such as Bruce Dern, Alan Hale Jr., Dennis Hopper, and L.Q. Jones.