Passing through a town, a farm boy aspiring to be a bounty hunter rescues a woman who has been tricked into working in its brothel and the two travel towards his father's ranch.
After his girlfriend dies in childbirth, Confederate deserter John Warner travels to Mexico, where the woman's father, Don Pedro Sandoval, grudgingly hands over his child. But with no locals willing to provide milk, the baby dies. Rounding up a group of rebels, Warner goes on a rampage through northern Mexico, with the ultimate goal of taking down Sandoval in this gritty Western.
Don Juan, the governor of a Mexican province, arrests Manuel, the fiancé of the beautiful heiress, Virginia. When Quintana frees Manuel, Don Juan kidnaps Virginia to force her hand in marriage. The ceremony is interrupted in a violent battle.
Renegade Confederate soldiers take over a frontier town, but after they molest a young black woman, a group of ex-slaves arm themselves and counter-attack.
Photographed by famed cinematographer Laszlo Kovacs just before embarking on EASY RIDER (1969), Mark of the Gun is a classic western tale of outlaws and the women they love.
Braddock is an influential and highly respected citizen of the town of Two Arrows. He also represents a group of Mexican outlaws led by Valiente. Braddock plans an important robbery with only two young men, Loring and Parker, standing in the way of the bandits.
Luke Barrett, having lost his memory due to an accident, does not realize that Dingus had killed his wife and brother to take possession of the Barretts' land and money. At first Luke trusts him, but while looking for his forgotten identity he discovers the truth.
Returning home, Ross Logan immediately gets into conflict with the Carranza gang, which had just crossed the Mexican border and has occupied a nearby Hacienda. After his brother is killed he plans a cold blooded revenge for which he separates the gang's most dangerous members by using their individual weak points and the general discordance amongst them. The time for the final confrontation is set by the astronomically interested Logan amidst an eclipse.
Johnny King, a rebellious drifter, sets out to avenge the death of his mentor and friend, Steve, after he has been murdered for his land by the Ward Brothers. After causing some trouble for the Wards, Johnny faces a new opponent, his outlaw friend, Meredith.
When the lead robber in their gang steals the money from his two companions, a cat and mouse/back and forth game plays out as the men try to get the money for themselves. But another player, the heir of the sneaky gang leader, is also on the hunt...
The bandit Pratt, looking for Tim, who is responsible for the death of his two sons, attacks a caravan killing all the passengers. Harry, the vagabond, after having robbed the dead, casually meets Tim and they become friends. Running away together from Pratt, they reach Harry's farm, but their hiding place is soon discovered.
After a stagecoach is robbed and the passengers murdered, a long and tangled series of surprise attacks and murderous double-crosses, leaves the coach's strongbox in the hands of the killer Lasky. It is up to the legendary hero Sartana to track down the missing money and determine just who is ultimately behind the grisly robberies and killings.