The Savage Seven (1968)

A motorcycle gang terrorizes a Native American reservation -- until the gang's leader, Kisum (Adam Roarke), falls for waitress Marcia Little Hawk (Joanna Frank). The two groups soon put aside their differences to team up against crooked Fillmore (Mel Berger), who employs Marcia and her brother, Johnnie (Robert Walker). But Fillmore decides to encourage dissent among them, arranging for the death of a gang member and framing a Native American -- which leads Kisum to plot an attack on the town.