Scout Jess Remsberg (James Garner) is searching for the man who killed his Apache wife, and his travels have taken him to this stretch of the desert where he is well aware that the tribe has a pressing and dangerous presence. As he rides, he notices up ahead an exhausted woman on an equally exhausted horse, and on seeing them collapse he is about to make for her when a couple of Indians appear in his field of vision and he springs into action. With a single bullet he takes down one of the advancing braves, but misses the other; he still manages to reach the woman and drag her to cover - but who is she and what is she doing out here all alone?
Well, there's a story, and you'll learn all about it if you watch Duel at Diablo. The history of violence in the movies often takes in horror movies, thrillers too, but perhaps the other main genre to latterly embrace such devices was the Western, which has been forgotten as it fell from favour. Ralph Nelson, our director here (he takes a rather grand possessive credit in the opening titles), would push back the boundaries of what was acceptable in movie violence with a Western, only it wasn't this one, it was the would-be consciousness raiser Soldier Blue, but it's easy to see him straining at the leash of what was acceptable with this film from a short while earlier.
Nelson doesn't linger over the bloodshed here, but it is considerably more brutal than the likes of Stagecoach or High Noon, if not necessarily a better film. It did provide much of the reason that the film's fans recall it today, as it came across as far more gritty than what the era was used to, in Hollywood Westerns at any rate as the European variety were already getting their hands dirty. But the other reason this stuck in the mind was that odd cast, with a couple of TV cowboys, one past one present, one of Ingmar Bergman's favourite actresses, a British star of a much bigger movie from that same year involving animal preservation (the horses here could have done with some of that), and a pioneering megastar.
That megastar, who was a far bigger deal in movies than Garner was, was Sidney Poitier, doing his bit to remind us that many cowboys in the Old West were black, not something you'd have noticed from the first sixty years or so of the genre. Here he plays Toller, a gambler who has just made money selling horses to the army division of Bill Travers (playing the Scottish Lieutenant McAllister, or Scotty for short in a Star Trek fashion); Toller finds that because the beasts have not been broken in, he must accompany Scotty on his journey to another fort on an ammunition run if he wants to get the rest of his cash. Jess goes along too, because he has been persuaded that the territory is so dangerous that the army needs his services.
As was usual in Poitier's films, there was a racial element to this, except that all the characters apart from Dennis Weaver's Willard Grange accept Toller for who he is and it is the question of Grange's wife Ellen (Bibi Andersson, the woman Jess saved at the beginning) which vexes them all. Ellen, you see, was captured by the Apaches and had a baby with one of them which has made her an outcast in white society, even though it's doubtful she had much of a say in the matter. The infant becomes a bone of contention between the film's factions, with Jess obviously attracted to Ellen as the woman who could be the ideal replacement for his lost love, or she would if she were not already married. There's a fair amount of coincidence employed here to work all of this out, but the action is plentiful, the politics not battered over the audience's heads, and Duel at Diablo a solid effort without being stodgy - more than could be said for Soldier Blue. Catchy music by Neal Hefti.