TV REVIEW : TRICKS SPOIL THE TREATS IN HBO’S ‘WORST WITCH’

This Halloween season’s mixed bag of ghostly family television fare includes a mixed contribution from Home Box Office.

“The Worst Witch,” a 70-minute, made-for-cable musical, based on Jill Murphy’s charming book about an upper-crust boarding school for young witches, premieres Wednesday at 4:30 p.m. It also will be shown Saturday at 8:30 a.m., Sunday at 6:45 p.m. and on Oct. 30 at 7:30 p.m.

Fairuza Balk plays bumbling student Mildred Hubble, whose misadventures in school threaten to get her expelled. Poor Mildred ruins potions, can’t undo spells and crash-lands her broom. A snooty classmate taunts her and creepy teacher Miss Hardbroom seems to have it in for her.

Balk, who was the somber Dorothy in Disney’s gloomy “Return to Oz” last year, doesn’t get to smile much here, either.

Don’t look for spooky thrills. St. Michaels School in Great Britain, where the show was filmed, an imposing gothic stone structure, should have been a sufficiently tenebrous setting, but instead, unlike in the book, the school is cozy, with well-lit halls and classrooms and snug, pink-blanketed beds.

For the most part, the treats are supplied by cast members Diana Rigg, Charlotte Rae and Tim Curry, who camp it up throughout, in a plot played for laughs, not chills.

Hip, Las Vegas-style wizard Curry’s big solo is a Halloween video, rather oddly thrown in as part of the hodgepodge that makes up a fitful musical score.

Rae, expert as kindly headmistress Miss Cackle, relishes a dual role as evil Agatha, plotting the school’s downfall. Sporting a pink wig and a Scarlett O’Hara accent, Rae seizes the opportunity for some outrageous mugging, as she and her band of cohorts, dressed in cartoon colors, frolic in the woods.

Hard-nosed Hardbroom, a firm believer in intimidation as an educational tool, is a role made for Rigg. Tight-lipped, swathed in black, Rigg’s sudden entrances are delightfully unnerving, her sweeping exits juicy occasions for one-liners.

However, despite the star turns, the show comes up disappointingly short in the tricks department, thanks to mismatched music, scenes carelessly patched in like filler and inept special effects.

Broomstick aeronautics are a basic element in the story, but obvious process screening, above the waist close-ups and an erratic wind-machine create some of the most unconvincing flying scenes since Buck Rogers.

And that’s no treat.