Northern Italy in 1944, and a small village are lined up by the Nazis and asked by Captain Von Hecht (Sergio Fantoni) where the partisans are. None of them are willing to admit they know, thus his superior loses patience and orders them all machine gunned to death, all of this while the children of the village watch from a hidden vantage point in the hills and are powerless to assist their relatives or prevent the massacre. They have become a child army of partisans themselves, and when shortly after there is an American warplane flying overhead from which parachute troops led by Captain Turner (Rock Hudson), the children's leader Aldo (Mark Colleano) takes a great interest in their wellbeing...
Alas, the Nazis get there first and perform yet another massacre on the landing Americans, but you don't kill off your star in the first couple of minutes, even if you're not giving him anything to do for the next twenty, thus Rock is the sole survivor, and he's a man with a mission to blow up a nearby dam which will foil the Nazis, er, somehow, though you'd have to presume it would also greatly inconvenience the Italians too, and in this instance they were presented as the good guys thanks to the kids representing some armed resistance or other. There's a bit in Joseph Heller's Catch 22 where an elderly Italian says his countrymen essentially take the path of least resistance and therefore prevail, which rang true here.
In this case the formerly fascist Italians have by the start of the plot changed their tune, but the theme of Hornet's Nest wasn't political so much as it was social, detailing the corruption of the young when war was involved. This was a subject close to the heart of Hudson's leading lady Sylva Koscina who played the nurse Bianca, kidnapped by the youths to attend to Turner while he is unconscious (he was knocked out when he landed). Koscina had witnessed some harrowing sights when she was a little girl in the then-Yugoslavia before her family had fled to Italy which was why she signed on for this, believing it would act as a consciousness-raising exercise. However, she was to be disappointed as most often the reaction was it was in terrible taste.
The scenes where the children, most of them young teenagers anyway, take up arms and for example conduct a raid on a Nazi base, gunning down countless grey-uniformed extras, made all too many audiences forget about any message making and throw up their hands in disgust, which funnily enough was the reaction they were intended by the filmmakers to regard war in the same fashion. Nobody here is untouched by the brutality, to the extent that there is nobody to particularly sympathise with in that you can feel sorry for the kids, but the cruelty they exhibit is less than endearing (almost gang-raping the nurse), and while Bianca may seem like the heroine she is all too keen to shop Turner and his young followers to the Gestapo, which prompts the American to rape her anyway to keep her in line.
It was brave to paint the characters in such morally compromised colours, but it didn't make for much of an entertainment, even for fans of men on a mission war movies of which this was technically one. It was kind of like watching a playground game of soldiers taken a step too far, a film which featured youngsters but could not in all honesty be deemed appropriate for them, which left its audience as the war is hell brigade who relished being told what a dreadful time is had by all in the world's conflicts. Once you've seen the troubled teen Aldo manning a machine gun nest and mowing down the opposition you can wonder if what you're watching has crossed the line from sober, ashen-faced moralising and into sheer exploitation, though there is a tragedy right around the corner as a consequence of those actions. So this was a tad too serious-minded to be classified as trash in spite of the bloodthirsty nature of the mayhem, and with the usually charming Hudson refusing to appeal to the viewer in his accustomed manner it was more uneasy curio than anything. Whistley music by Ennio Morricone.