It is not the two-ton, rusty-scaled, fire-breathing, airborne dragon that does irrevocable damage to "Dragonslayer," but its young family. No bigger or urlier than zoo alligators, the babies manage, in one greedy snack, to destroy the family suitability of an otherwise charming and amusing movie.

As a sixth-century adventure story with the latest fashion in special effects -- mechanically operated villains created under the direction of Brian Johnson of "Alien" and "The Empire Strikes Back" -- the film, made under the Walt Disney aegis, should have a wide appeal. The Tolkien industry and the game of "Dungeons and Dragons" has given British mythology a new popularity. Lots of young people who don't necessarily know how Congress works can tell you in amazing detail the attributes and limitations of sorcerers and dragons.

Furthermore, the picture is done with cleverness and dashes of wit. Its hero, played by Peter MacNicol, is an engagingly young twit whose education as a sorcerer was cut short, and who is therefore trying desperately, and without notable success, to learn on the job. The tolerance of the heroine, played by Caitlin Clarke, is severely tested. And the princess he saves against her will and sense of noblesse oblige is understandably exasperated.

Best of all are the canny old pragmatists -- Ralph Richardson as Ulrich the sorcerer, Sydney Bromley as his sidekick, and Peter Eyre as the king of dragon-ridden Urland. "We don't do tests!" the old sorcerer's ancient assistant proclaims to protect his master, who does one anyway and flops. Richardson's wobbly ferocity, as he mumbles about the uselessness of magic if you can't turn lead into gold, is marvelous. And the apparently cruel king, who feeds one lottery-chosen virgin a year to the dragon, is politically vindicated when the alternative to such appeasement is tried.

In the midst of all this fun, there are some vicious scenes, the worst of which has those baby dragons eating chunks of the bloody dead body of the princess. One would say that this renders the film unfit for children, if that didn't imply that, with maturity, people grow to appreciate such things.

DRAGONSLAYER -- At the AMC Skyline, Beltway Plaza, Bradlick, Embassy Circle, Hampton Mall, K-B Baronet West, K-B MacArthur, Mercado, NTI Tysons Cinema and Roth's Parkway.