The move follows the strange-but-true tale of Robert Leroy Parker and Harry Alonzo Longabaugh, sons of devout and impoverished families who in the long tradition of American pioneers set out in search of a different life. But instead of homesteading a spread of land, they reinvented themselves as Butch Cassidy and Billy the Kid.

The movie is based on a true story, which began shortly after the Civil War. The outlaw known as Butch Cassidy, born Robert LeRoy Parker on April 13, 1866, was the eldest of 13 children in a Mormon family in Utah. His admiration for a young cowboy named Mike Cassidy and a stint as a butcher inspired his nom de crime.