Someone had a great idea for the plot of a movie. "Hey fellas," he probably said, "I got a great idea for the plot of a movie. We'll show this French town at the end of World War One that gets evacuated just as the Germans retreat. All except for the inmates of an insane asylum, who break out and take over the town, not knowing that the Germans have prepared time bombs to blow the whole place up in 24 hours.

"Then the British send in a demolition expert, and the lunatics promptly make him king. Before it's all over, he realizes that this town full of screwballs is really an oasis of sanity in the midst of these armies."

It was a good plot. Well-done, it could have been another Morgan: hilarious, terribly sad, and needling us with the not-too-trite suggestion that lunatics may be the only sane ones after all. Poorly done, and King of Hearts was poorly done, it leaves only a sense of disappointment, of lost opportunity.

The first problem of execution is its clumsy, slapstick portrayal of the German and Allied troops. The movie goes with the Hogan's Heroes school of soldiers for both sides of the conflict. The Germans have names like Hamburger and, as in the latest Gillette ad, go through the old gag in which the commander laughs at the subordinate's joke, stops laughing, and then glares while the subordinate gulps. At one point a young lieutenant with a stubby mustache comes running in shouting something about Mein Kampf, and is told. "Later, Adolph, later."

The British soldiers are similarly hammed up. (The British are actually Scottish. I suppose this is so the kilts and Highland flings could make a troubling parallel with the costumes and pagentry of the lunatics. But the sterotoype is of a British Soldier.) The sputtering British commander stops everything at 4 p.m. for his cup of tea.

The slapstick approach is unfortunate. It seems to me that if one is trying to question the sanity of warfare or society or mankind, one should start with an attempt at authenticity in portraying the soldiers. It is reality, not a warmed-over Abbot and Costello version of it, which is being called to account.

Bates, fresh from his near-success in Zorba the Greek and Georgie Girl, is almost as disappointing as the rest of the movie. Where the director seems confused about what he is satirizing, Bates seems confused about what he is saying. He hams up the funny parts too much, and, although Tony Quinn is not here to overshadow him, he still seems to wander through the rest.

The film is not without its good touches. The scene pictured above with Bates' presenting his credentials in formal application for admission to the lunatic asylum, is one. But the good scenes are few; the could-have-been-good ones are many.