The French/Italian/British King of Hearts (Le Roi de Coeur) takes place during World War I, but it might as well have been the Vietnamese conflict so far as its youthful core audience was concerned.
Overacting outrageously, Adolfo Celi plays British colonel Alexander MacBibenbrook, who orders mild-mannered Scotsman Pvt. Charles Plumpick (Alan Bates) to undertake a life-or-death mission in a tiny French village. While evacuating the town, the Germans have left behind a time bomb that will explode at midnight; Plumpick must defuse that bomb.
Upon his arrival in town, Plumpick discovers that it is far from deserted. A group of inmates from the local insane asylum, left behind during the evacuation, have claimed the village for their own. Knocked unconscious, Plumpick awakens to learn that he has been crowned King of Hearts by the gentle lunatics.
None of the inmates pay any heed to Plumpick's warnings about impending doom, and when he attempts to lead them out of town, they are terrified at the prospect and scurry back to the safety of the village. Plumpick is finally able to render the bomb useless, whereupon the grateful inmates decide to stage a three-year celebration.
When Plumpick tries to leave, he is kidnapped by the loonies at the behest of beautiful inmate Coquelicot (Geneviève Bujold), who has fallen in love with him. Bound and gagged, Plumpick watches helplessly as the Germans and the British troops kill each other off in comic-opera fashion.
Finally set free, Plumpick weighs the horrible insanity of war against the more benign brand of lunacy represented by the inmates. The final image -- of a nude Plumpick carrying a birdcage, knocking on the doors of the asylum, and demanding that he be accepted -- was reproduced for the print ads of King of Hearts, effectively giving away the ending.
An essential date film of the 1970s, King of Hearts was often released to campus movie houses in tandem with a pair of cult-favorite short subjects, the animated Bambi Meets Godzilla and Lenny Bruce's Thank You Masked Man.