"Wind in the Willows," a musical getting its world premiere at the Folger Theater, has been adapted, very loosely, from the Kenneth Grahame children's classic. Grownup purists may be affronted to see so many of their memories shattered and rebuilt. It would be nice to say that the rest of us should be charmed.

Unfortunately, while the show has crowd- pleasing moments and flashes of invention, it's theatrical fluff, like the bunnies that clutter the stage. Grahame's fable -- concerning the adventures of Toad, Mole, Rat et al. around the Riverbank, the Wild Wood and out in the Wide World -- is a full- course feast. This musical is a big fat marshmallow.

Why set "Wind in the Willows" to song and dance? This show isn't supplying convincing answers. It plays like a committee creation, lacking a fresh and singular vision -- the unifying impulse that would move matters to a head.

The undistinguished libretto -- which, among other changes, downgrades Grahame's charming "animal etiquette" to bathetic boy-meets-girl -- is by Jane Iredale. The undistinctive music, heavy on Broadway bubblegum, is by William Perry -- and not well served by the flat vocal arrangements.

And the humdrum lyrics, which run to "heart could sing . . . every day was spring," are by Roger McCough and his two partners. They're a busy triumvirate of wordsmiths, who don't even shrink from hammering away at a Christmas carol from Grahame's book, revised and set to music here.

The dauntless Folger has mounted one of its typically stylish productions, complete with movable forest and exploding motor car. John Neville-Andrews does yeoman's work directing performers of varying abilities -- many of whom, their talents aside, look disconcertingly musclebound.

The exceptions are Ken Jennings as the ridiculously puffed-up but lovable Toad, who makes his first entrance in aviator's garb, bouncing on a pogo stick; Vicki Lewis as the mousy Mole, squinting through her spectacles; and, best of all, P.J. Benjamin, who, as the Chief Weasel, leads his squad of black-leather-suited thugs with acrobatic energy and malevolent charm.

His renditions, a la Elvis Presley, of "Evil Weasel" and "I'm Bad," plus the Weasels and Stoats' tap-dancingly devilish "We're Moving Up in the World," are in welcome opposition to the prevailing wind. WIND IN THE WILLOWS -- At the Folger through September 18.