In 1869, a train bound for Colby, Texas, USA, detained the murderer Cavendish (William Fichtner) who was about to be sent to the local execution. Unexpectedly, Cavendish escaped with the help of his accomplices on the way. The Indian killer Tonto (Johnny Depp) and federal prosecutor John Reid (Armie Hammer) who were in the prisoner's car went through all kinds of dangers and escaped by chance, but they were thrown into prison by the latter. John's brother Dan (James Badge Dale), a mounted policeman, led his men to hunt Cavendish, but was brutally slaughtered by the other party. John, who was traveling with him, regained his life with the help of Tonto who escaped from prison, and learned the true identity of the traitor in the mounted police. For this person who should have died, perhaps only by wearing a mask can justice be upheld. White people and Indians, two people who originally had no intersection, embarked on the road of revenge...