"Stoned" is a heavy trip. The ABC Afterschool Special, at 4 today on Channel 7, is more subtle and sophisticated than one might expect a cautionary tale about marijuana to be.

To the credit of writer-director John Herzfeld, the message delivered is more a warning against over-reliance on psychological crutches and chemically introduced escape than it is a tirade against a plant; no signs of "Reefer Madness," although a teacher is heard to warn students that pot "could cause chromosome damage or sterility in males, or birth defects in females." The jury may be out on this one for a hundred years, however.

Scott Baio plays the high schol student who feels unpopular and shy until a few joints from a trio of layabouts cause him to see trees and life in a whole new light. But the euphoria has its dark side, a girl he adores is turned off by the giggliness and irresponsibility of his dependence on the weed. And he learns his lesson but good after a terrible but plausibile accident in a lake involving his older brother (Vincent Bufano, a sort of thinking man's Sylvester Stallone).

While Baio, who normally wastes his time on "Happy Days," puts in a solid, thoughtful performance, Largo Woodruff as Felicity, his girlfriend, makes an even fresher impression -- another promising find for this series of specials which has introduced many bright young actors over its eight proud years on the ABC Television Network.