The laughs that come backstage

It’s about as plausible as your average stage — or movie — musical, but “Opening Night” proves a funny and sexy if decidedly slight backstage comedy. Anchored by an engaging turn by Topher Grace as Nick, a failed Broadway performer turned stage manager, the film, directed by Isaac Rentz from a script by Gerry De Leon and Greg Lisi, packs plenty of music and mischief into its brief running time.

On the opening night of the Broadway musical “One Hit Wonderland,” a jukeboxtype tribute to artists known for one — and only one — Top 40 hit song, Nick must keep the show’s eccentric cast and crew in line through a wacky series of conflicts and obstacles.

These players include pretty understudy — and Nick’s ex-girlfriend — Chloe (Alona Tal), who must jump into the show after the jaded leading lady (Anne Heche) suffers a concussion; the musical’s womanizing star (’N Sync’s JC Chasez, as himself); a cocky gay dancer (Taye Diggs) who hilariously competes with a shameless diva (Lesli Margherita) for a hot new cast mate (Diego de Tovar); and the show’s hyper-obnoxious producer (an over-the-top Rob Riggle).

Enjoyable musical numbers, both on stage and off, accompany the fast-paced action, with such pop earworms as “Rock Me Amadeus,” “Living La Vida Loca,” “I Melt With You” and “I Know What Boys Like” dotting the evocative soundtrack.

“Opening Night.” No rating. Running time: 1 hour, 23 minutes. Playing: Arena Cinelounge Sunset, Hollywood.