This is one of a series of ferociously violent westerns produced by a group of left-leaning American expatriates who fetched up in Spain in the late 1960s and early 1970s. Director Alexander Singer once made the now forgotten urban mini-masterpiece A Cold Wind in August, but he seems less happy here. Nevertheless, he makes excellent use of the landscape and manages to generate some real tension. There's also a bizarre supporting turn from English character actor Percy Herbert, who holds his own against such western stalwarts as Stuart Whitman and Lee Van Cleef as the titular native American warrior.

The title character is a US army Captain of Native American descent who is asked to investigate the murder of an Indian agent. His only clue is "April morning", the last words spoken by the victim. Can he unravel the mystery before the clock runs out?