It has probably been some years since "Reefer Madness," the high-school perennial about the evils of marijuana, has scared anyone. Where it is still shown, the dire warnings about pot, sex and jazz greatly amuse the sophisticated teenagers of today, who find them indistinguishable from the warnings in "The Music Man" against smoking cigarettes, playing pool and saying "swell."

If the high schools want to go back to scaring kids about drugs, they might send them to "Who'll Stop the Rain," a film based on Robert Stone's novel "Dog Soliders." It's about cocaine ruining the lives of three well-meaning people, and it's plausibly enough done to very, very frightening.

A war correspondent in Vietnam sees the opportunity to buy cocaine, which he persuades a sailor friend to import for him to the United States. The friend brings it to the journalist's wife.

The three have similar rationales for what they're doing, all the kind of commonplace talk one hears from everyone these days about how life is crazy now anyway, and coping so difficult. The journalist blames the war. Elephants, he explains, have been declared enemy agents because they carry supplies, and "in a world where elephants are pursued by flying men," it is only natural to want to get high. For his wife, who works in her father's bookshop in Berkeley, it's the difficulty of coping with the stress of daily life. For the friend, it's because "all my life, I've been taking s--t from inferior people."

Why not, they all decide, seize this opportunity to get rich? Especially since the "basically moral" standards they've had before have always admitted breaking the law by importing, selling and using grass.

Michael Moriarty, who plays the journalist, looks remarkably like John Dean, and the way his character approaches this illegal step, with timidity, philosophy and an air of decency, is riveting. Tuesday Weld, as his unglamorous, equally timid and nice wife, and Nick Nolte, as the friend whose primitive humanity keeps breaking through his surface toughness, are equally effective.

Almost from the beginning, these three are shown as being caught in the crossfire on a battlefield where gangsters and crooked law agents are engaged in serious warfare. The ingenuity and desperation they muster is pathetic, as you watch them madly driving into hiding - through the eyes, binoculars and radio equipment of their pursuers, who easily follow their every move.

Because of the round portrayal of the characters, with their strengths and weaknesses both shown, and because of the way the film builds, it comes out as a sophisticated but very moral drama. Just the thing to scare the children.