A good joke about musicals: In the 1989 movie "The Tall Guy," a struggling actor gets the lead role in a proposed musical adaptation of "The Elephant Man." The show's title? "Elephant!"

Exclamation points have become shorthand for musicals at their slap-happy, vapid worst, but certain shows genuinely earn that celebratory punctuation mark. "Oklahoma!" is one example. "Oliver!" is another -- only not as it's being performed at the Olney Theatre Center.

Dark and sluggish, Lionel Bart's beloved adaptation of Charles Dickens's "Oliver Twist" has lost its excitability. It's "Oliver," period, and so gloomy it feels shrouded by parentheses.

Director Brad Watkins's production begins promisingly enough. A platoon of workhouse tykes in grubby coveralls trudge up from the orchestra pit in the Olney's wide, handsome new theater. The kids sit at the long table on James Kronzer's imposing set -- a warren of wooden steps and platforms invoking the interlocked strata of Victorian London -- and they gradually rev up into the dreamy, zippy "Food, Glorious Food." Bart's songs make the point again and again: Hungry and ill-used, the characters are indomitable.

The performance, though, is mechanical. Musical director Christopher Youstra's handling of Bart's dramatic, jubilant score is more clockwork than supple -- you can almost hear a metronome clicking along with the small orchestra's cautious notes.

Ilona Kessell's choreography is similarly ginger. When young Oliver (the appealing J. Bradley Bowers, alternating with Ethan Langsdorf-Willoughby in the role) hooks up with the teenage Artful Dodger and old Fagin's charismatic den of thieves, Bart rapidly seals the encounter with a great sing-along, "Consider Yourself." Kessell gets a lot of people involved in the number but never taps into the song's infectious high spirits. Here and throughout, the dancing is active but not lively.

The show's primary spark comes from Peggy Yates, a saucy, high-spirited charmer as the doomed Nancy. "It's a Fine Life," "I'd Do Anything" and "Oom-Pah-Pah" are all good-time songs, and Yates puts them over with flair. She's a beam of sunshine in Watkins's coal mine of a production.

Watkins apparently sees "Oliver!" as a tale fraught with danger, so he has designer Charlie Morrison keep the lights dim, as if filtered through a cloud of soot. By the second act, the theater is suffused in stage fog. The effect isn't sinister, though; it's just dreary. And when the opportunity arrives to put a real scare into the audience -- when, that is, the fearsome Bill Sikes arrives to bellow "My Name" -- boyish Brian Sgambati turns out to be the wrong man for the part, more all-city quarterback than scourge of London.

Shakespeare Theatre Company veteran Andrew Long makes a wily, witty Fagin, keeping his young criminals off-balance like a playful uncle with a secret or three to keep. Yet he never quite wraps the audience around his finger in the crowd-seducing "Pick a Pocket or Two" and "Reviewing the Situation" -- more flat numbers when you're counting on fun. It's pretty elaborate, this "Oliver!," with the vast, multilevel set and a cast of about 30, but it turns out to have precious little showbiz in its soul. It's slow-footed, heavy . . . alas, an elephant.

Oliver! Book, music and lyrics by Lionel Bart. Directed by Brad Watkins. Costumes, Howard Vincent Kurtz; sound design, Neil McFadden. Through Dec. 31 at the Olney Theatre Center, 2001 Olney-Sandy Spring Rd., Olney. Call 301-924-3400 or visit www.olneytheatre.org

Meghan Touey as Bet, J. Bradley Bowers as Oliver and Peggy Yates as Nancy in "Oliver!"