It's hardly ever a good idea for a stage musical to replicate the movie that inspired it. "Saturday Night Fever" is Exhibit A in any trial of this theory.

While the dance ensemble in The Gateway's summer season finale achieves a pulsating simulation of burning off youth's excess energy, figurative opening-night thermometers barely rose above air-conditioned room temperature. The 1999 Broadway stage adaptation crams in every plot detail of Norman Wexler's 1977 screenplay. Crosscutting cinematography made the movie feel less rushed, but here the plot careens from one element to the next -- from parents playing favorites to gang warfare, from loss of virginity to loss of faith, from jealousy to pregnancy and death -- it's an expository blur.

A few heartfelt songs contribute to a more satisfying Act II, but "Fever," as directed by the very capable Keith Andrews, rarely spikes one.

Luke Hamilton in the John Travolta role of 19-year-old Tony Manero recovers from a tentative start to preen plausibly as the "disco king of Bay Ridge." Jenny Florkowski makes a formidable match as his "queen," Stephanie, a Brooklyn girl who finds Manhattan so much more refined. The pair's "More Than a Woman" dance is lovely.

Haley Hannah, as the dance partner Tony dumps for Steph, isn't given much to work with in emotional buildup to her torchy "If I Can't Have You." Similarly, Jeremy Greenbaum's Bobby and Jillian Butterfield's Pauline, sweethearts since forever, are barely established as characters before their defining duet, "How Deep Is Your Love."

Bobby is the most sensitive of Tony's numskull buds (Corey Mosello, Michael Siktberg and Michael Carrasco), who harmonize with Greenbaum on "Jive Talkin'."

Amma Osei as the bluesy chanteuse at 2001, the nightclub where Tony and Stephanie compete for disco royalty, delivers a robust "Night Fever" with Justin Columbo as the DJ in pimp duds (costumes by Dustin Cross). Brandyn Day as Tony's brother struggles to make his "Father Frank" plot diversion relevant to this decidedly secular scenario.

Music director Sonny Paladino and choreographer Richard Hinds bring a potentially foot-tapping vibe to the Bee Gees' hit parade. But brevity keeps even the infectious "Stayin' Alive" from building much momentum.

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Still, Adam Koch's dazzling, versatile set and a nimble dance chorus may fool you, if only fleetingly, into thinking you're back in the disco decade.

WHAT "Saturday Night Fever"

WHEN | WHERE 8 p.m. Wednesday, Friday and Tuesday, 2 and 8 p.m. Thursday, 3 and 8:30 p.m. Saturday, 2 and 7 p.m. Sunday through Sept. 12, with 2 p.m. show on Sept. 9 at Gateway Playhouse, 215 South Country Rd., Bellport

TICKETS $54-$89; 631-286-1133, pacsc.org