Once Upon a Time in the West (1968) on Netflix

Plot summary

A railroad is being pushed across the Arizona desert toward the town of Flagstone. Jill McBain, who married Brett McBain a month earlier in New Orleans, reaches his ranch, Sweetwater, and learns that he and his three children have been murdered there. The killers ride for Frank, a gunman paid by Morton, a railroad baron who wanted McBain frightened rather than killed; McBain had meant to build a watering station on land the railroad must cross, and Jill now owns that land. At the Flagstone station a stranger who carries a harmonica shoots three men who were waiting to ambush him, and the ranch killings are blamed on the outlaw Cheyenne.