Growing up on a rich plantation in Louisiana, Pat Garrett spent his youth hunting on his family's vast estate. After the war, his family's fortune fell on hard times and as a 19 year-old, Garrett hit the open trail.
In Texas, Garrett becomes a ranch hand and, when the buffalo hunts start, he heads into the wilderness to make his living as a buffalo hunter. In 1878, Garrett kills a man for the first time when he gets into a fight with another hunter. Without any eyewitnesses to testify against him, Garrett escapes from the debacle a free man and heads deeper into The West... to the New Mexico Territory.
When he arrives in Fort Sumner, Garrett is an imposing figure – 6'3" and clothed entirely in buffalo skins. He's a hard-working man looking for any kind of job, and he finds it as a ranch hand, a saloon owner and a "professional" gambler. While tending his saloon, Garrett becomes acquainted with Billy the Kid and the other members of Billy's Lincoln County War faction, The Regulators. Garrett's familiarity with Billy makes him an ideal choice when the position for sheriff opens up in Lincoln County – and cattle baron Thomas B. Catron of "The House" makes sure to secure the votes Garrett needs to win.
At first, Garrett's intentions as sheriff are noble. He's appointed with the sole purpose of bringing Billy the Kid to justice, and that's just what he sets out to do. Garrett is an expert tracker and a hunter since childhood. But as the hunt drags on, the attraction of being the man to catch Billy the Kid – and collect the reward that goes along with that distinction – goes to Garrett's head. After Billy's death, Garrett tries to use his newfound celebrity as the man who killed Billy the Kid to achieve a higher social status... but all that unfolds is a series of miseries that end in Garrett's murder years later by another gunman.