The real subject of "Snow White and the Seven Dwarfs" is not a poisoned apple but "the ambivalent relationship of mother and daughter." This point comes across with peculiar impact in Conrad Susa's opera "Transformations," which had its Washington premiere last night at the Wolf Trap Barns.

Susa's operatic treatment, using poems by Anne Sexton, brings vivid life and eerie overtones to the old myths and archetypes of the Brothers Grimm. These tales are, of course, a message spanning the generations. They embody such rigidly tabooed subjects as incest, cannibalism, madness and the death wish, and they warn about where they can drive us. "Hansel and Gretel" is the stuff of nightmares; "Rapunzel" and "Sleeping Beauty" might be fantasies by the Marquis de Sade. Sexton saw these implications with the clear eye of madness, the iron determination of one on the brink of taking her own life. And her intense poetic treatment is heightened by Susa's music.

If we don't run away screaming from such volcanic material, the healthiest reaction is to laugh at it. Sexton, Susa and the Wolf Trap Opera Company, which has done a brilliant job of producing the work, choose to laugh. There is sometimes a curious edge on their hilarity, but it makes a fast-moving, deeply absorbing two hours, set to music that ranges from tango and fox-trot to a spare, tense, dramatic idiom worthy of Stravinsky's "Renard" or "The Rake's Progress."

Wolf Trap has enlisted eight splendidly gifted young performers, equally adept at singing and acting, who slip easily from one archetypal role to the next as the music runs through 10 grim Grimm tales. Not all 10 are equally fine, though all are worth seeing. The best, on first exposure at least, were "Snow White," "Briar Rose" (alias "Sleeping Beauty"), "Rumpelstiltskin" (with the evil dwarf of the title role cast as a Truman Capote clone wearing green sneakers) and "Hansel and Gretel," which had an absolutely dazzling performance last night.

The three women of the cast have the best material and use it expertly: Phyllis Treigle, who takes the witch roles (and represents Sexton); Dawn Upshaw, totally convincing as a series of 15-year-old virgin princesses, and Luretta Bybee as a generic good fairy and helpful bystander. Alan Glassman played Prince Charming with a hint of the younger Sylvester Stallone. Gordon Hawkins was vocally rich and theatrically versatile in roles that ranged from a can of worms to an archetypal father. Darren Keith Woods supplied some of the evening's most pointed comedy, and Eugene Perry and Ned Barth both sang and acted well.

Peter Mark Schifter's stage direction was inspired, and Stephen Crout conducted a taut, idiomatic performance. "Transformations," repeated tonight and Aug. 23 and 25, is a special treat for connoisseurs.