Frothy, sentimental and thoroughly good-natured, Malcolm D. Lee's tale of coming-of-age at the roller disco doesn't have an original bone in its body, but it's as energetic, eager to please and endearing as a sloppy, wriggling puppy. Chicago, 1978: Newly motherless X (Bow Wow) — as in Xavier, not Malcolm — and his South Side friends Mike (Khleo Thomas), Junior (Brandon T. Jackson), Naps (Rick Gonzalez) and Boo (Marcus T. Paulk) intend to spend the summer at their local rink. But it closes down, and they're forced to venture over to Sweetwater's, a superswank North Side roller disco ruled by Sweetness (Wesley Jonathan), the very soul of sex on wheels, and his Lurex-clad crew of roller-bullies and bootie-shaking ladies. X befriends his gawky new neighbor, Tori (Jurnee Smollett), an "ugly duckling" whose lean-limbed swan-ness would make her X's natural love interest, except that her sexy mom (Kellita Smith) is obviously meant for X's recently bereaved father, Curtis (Chi McBride); even the faintest whiff of step-incest would be out of sync with the movie's innocent groove. X must come to grips with his own grief, learn to be responsible for his baby sister and work up the nerve to ask newly minted uptown girl Naomi (Meagan Good) — a down-to-earth South Side sweetie at heart — on a date. Unemployed engineer Curtis must find a new job and learn to love again. X's crew has to work up a routine that will win the annual Sweetwater skating competition, enriching them by $500 and showing Sweetness he's not so hot. Mike Epps and Charlie Murphy drop in periodically as neighborhood trash collectors, and Wayne Brady has a fine old time as D.J. Johnny Feelgood, the skate-off's enthusiastically funky master of ceremonies. Every narrative development is as formulaic as can be and the film's dramatic subplots are awkward at best and unconvincing at worst. But it's suffused with a sweetly goofy nostalgia for big 'fros, tight pants, old-school roller skates and pre-hip-hop boogie. Wesley Jonathan nails Sweetness' I-come-from-Planet-Perfection vibe, a combination of self-absorbed vanity and coolly disengaged flawlessness guaranteed to make mere mortals feel like insignificant insects; it's the star-making performance that keeps this clichéd soufflé from collapsing into a sodden mass.