Sergei Kowalski (Franco Nero) sits in a Mexican bullfighting ring, in the audience, and contemplates the clown show that has just trooped into the centre to perform their act. He is present because he knows the head clown, or rather knew him: he is Paco Roman (Tony Musante) who just a few short months ago was a revolutionary causing trouble for the tyrannical authorities, but now is lying low as he is a wanted man. Just how did these former allies get into this position, and what does the Polish want with Paco? To understand that we must go back in time to when they first met, when Kowalski had been hired to collect a bounty on his head and Paco was an escaped prisoner...
The phenomenon of the Mexican Western made by Europeans was a curious variation probably kicked off, as with the whole Spaghetti Western genre, by Sergio Leone, when he made The Good The Bad and The Ugly, which featured the revolutionary war in a central role. He would return to the trappings in Duck, You Sucker but the style was on the wane by that stage, yet for a while many Italian directors tried their hand at applying left wing politics to the Western and Leone's old friend Sergio Corbucci was one of those who took to the format like a duck to water (not a sucker to water), though arguably he was following the material of A Bullet for the General from the year before.
Anyway, The Mercenary quickly became a cult movie, as Bullet did, when it was shown around the world about 1970, especially popular with students to whom the politics and general breezy, vibrant tone appealed. Helping the film was the casting of two of the genre's most charismatic stars, Nero and Musante, Nero in particular well-suited to these with his handsome looks and ability to be tough but take a punch as well; Corbucci had made him a megastar with 1966's brutal Django, so that everyone from Jamaica to Japan and all points in between knew Nero's face and he became an idol of the screen. Musante did not have such a signature role, but his Paco came somewhere close.
Also showing up in the cast was celebrity bad guy Jack Palance, playing villainous, scheming Curly (did the makers of his Oscar-winning turn in City Slickers call that character after his supporting part here?). Curly is an opportunist out to make a profit from the revolution, but meets his match in Kowalski and Paco who by the time they encounter him have teamed up, mostly thanks to the Polish's knack for working out the best ways to stage acts of insurgency. And acts of gold and cash theft, which late-appearing leading lady Giovanna Ralli (whose career lasted around an incredible seventy years or more) observes seem to mean more to Paco than fighting the Mexican Government, despite the excuses he makes that he has the interests of the people of his homeland at heart.
For most of the movie you don't really buy that, but there's a political awakening for Paco when the powers that be opt to place a price on his head, mostly because he has been a troublemaker, but also because he is becoming a figurehead of the revolution. What was nice about The Mercenary was that the main cast enjoyed a genuine chemistry, especially between the double act of stars at its centre; everyone here worked very well together and their well-conveyed sense of fun consisted of most of the reason you kept watching, even as the plot began to be overstretched (it was a shade overlong at an hour and three quarters). Bits of business that contributed to that included Nero finding unusual places to strike his matches, a two-man brawl that veered into outright slapstick, and Palance completely naked (!), but despite it not being a wholly progressive type of movie, there was a tone of taking the spirit of the age and making the most of it, without being an acid Western. Even Spaghetti sceptics would be amused by this example. Fine music by Ennio Morricone and Bruno Nicolai.