''Hell is the impossibility of reason.'' Oliver Stone in ''Platoon.''

The settings are as exotic as they are varied, but all have been nightmarish images of hell on earth. In every film, a young man, whether through innocence, ignorance or a fatal error of judgment, finds himself trapped in a horror he cannot escape. Brutalized in a Turkish prison, caught in a senseless war in which he could be blown up at any moment, stalked by Salvadoran death squads or a Bolivian drug lord's assassins, the price of a man's miscalculation may be death.

Sudden, random and terrifying, the violence that has often erupted in Oliver Stone's movies has provided the lurid cinematic echo of a theme with deep roots in his own psyche.

As a teen-ager from a privileged background, all he wanted to do was flee from comfort to danger; in prep school he made inquiries about going to the Congo to fight as a mercenary, and he took up skydiving. In later years he would substitute drugs, alcohol and outrageous social conduct, acquiring a reputation for excess notable even by Hollywood standards and institutionalizing drug use as a recurring motif in his movies; but as a young man coming of age, the biggest high was courting death, and Mr. Stone made one of the most fateful decisions of his life when he dropped out of Yale to volunteer for combat duty in Vietnam, the most fearsome arena he could find. Next Comes Wall St. In the last year, Mr. Stone has turned 40 and earned the ultimate accolades of his profession, winning the Academy Awards for best picture and best director for ''Platoon,'' the movie he based on his own Vietnam War experience. He also got Oscar nominations for his screenplays for both ''Platoon'' and ''Salvador.'' Now Mr. Stone is about to begin shooting his next film, ''Wall Street,'' a story about the high risks and hard drives of big-money corporate raiders and traders.

On the surface, it seems a marked departure from his previous work; for once, no character will be eviscerated or dismembered with a chainsaw or have his head bashed to a pulp. Indeed, Mr. Stone said he saw ''Wall Street'' as a measure of personal change. ''There's no question that 'Platoon' is the end of the blood cycle,'' he said. ''I think I got everything I had to get out of me on that.''