Dan Evans is an impoverished rancher and Civil War veteran, who owes money to the wealthy Glen Hollander. One night, two of Hollander’s men set fire to his barn, warning his house will be next if he fails to meet his debts. The next morning, as Evans and his two sons William and Mark look for their lost herd, they stumble upon outlaw Ben Wade and his gang, who have used Evans’ cattle to block the road and ambush an armored stagecoach staffed by Pinkerton agents. As Wade’s outfit loots the upended stage, Wade discovers Evans and his two sons watching from the hills. Determining that they pose no threat to him and his gang, Wade takes their horses and tells Evans that he will leave them tied up on the road to Bisbee. Wade’s gang departs, and Evans rescues the lone surviving coach guard, Byron McElroy, left alive but severely wounded by Wade.
Wade travels with his gang to Bisbee to celebrate at the local saloon and divide up the loot, then chooses to stay behind to enjoy the company of the barmaid while his gang departs. Evans arrives separately with McElroy and delivers him to lawman Doc Potter, then tries in vain to negotiate with Hollander, who shoves him to the ground and departs. Enraged, Evans barges into the saloon looking for him, but instead encounters Wade emerging from an upstairs room. Evans coaxes a few dollars from Wade over the trouble the outlaw has caused him, delaying the outlaw long enough for the railroad men to ambush and arrest him.
The railroad’s representative, Grayson Butterfield, enlists McElroy, Potter, Tucker (one of Hollander’s men), and Evans, to deliver Wade to Contention, where Wade will be put on the 3:10 afternoon train to Yuma Territorial Prison. Evans requests a $200 fee (equivalent to $5,300 in 2019) to deliver Wade for transport, which Butterfield accepts. From Evans’ ranch, McElroy arranges for a decoy wagon driven by the town marshal to distract Wade’s gang, now led by Charlie Prince, with the real prisoner transport departing later that night.
During the journey, both Tucker and McElroy provoke Wade, who in turn kills them. Wade attempts to escape, but is stopped when William appears, having followed the group all the way from the ranch. When the group is then attacked by Apaches, Wade kills the attackers and escapes to a Chinese laborer construction camp, where the foreman captures him. Evans, William, Potter and Butterfield arrive to regain custody of their prisoner, but the foreman and his posse are unwilling to give him up, and a fight ensues. The group manages to escape, but Potter is killed in the process. The rest of the group arrives in Contention hours before the train’s arrival time and check into a hotel, where several local marshals join them.
Wade’s gang members ambush the decoy wagon, killing Marshal Weathers and interrogating the lone survivor before killing him and departing for Contention. Upon arrival, Prince offers a reward to any citizen who helps rescue Wade, and numerous men volunteer, causing the town’s marshals to desert immediately, only to be killed by Wade’s men when they try to surrender. Butterfield resigns as well, but agrees to keep William safe so that Evans can complete the mission.
Evans escorts Wade out of the hotel, and the two make their way across town, evading continuous gunfire from the gang and the townsmen. Wade surprises Evans and nearly strangles him, but relents when Evans reveals that delivering Wade to the train is not only to provide for his family, but to restore his own sense of honor, and give his sons something good to remember him for. Wade then admits he has already been to Yuma Prison and escaped twice, and agrees to board the train, allowing Evans’ contract to be fulfilled.
Wade helps Evans evade his gang, and as he finally boards the train, congratulates Evans, but Prince appears from behind and shoots Evans despite Wade’s order to stop. Wade steps off the train, and when Prince returns his gun belt, abruptly executes Prince along with the rest of his gang. William appears and draws his gun on Wade but does not kill him, instead turning to his dying father. Wade boards the train and politely surrenders his weapon. Evans dies as William tells him he accomplished his mission and got the money. As the train disappears around a bend, Wade whistles, and his faithful horse pricks up his ears and gallops after the train indicating that Wade is already planning his escape.