Here it is at last, the plump girls' feelgood, romantic comedy of a musical, whose dancing heels take a knockout kick at racist bigots in downtown Baltimore 45 years ago. Hairspray catches the heady, hopeful atmosphere of America teetering on the verge of Sixties cultural and political change. Rhythm and blues and Motown, then in their earlier stages, pump out the musical's seductive beat in the hectic dynamism of Jack O'Brien's production with Jerry Mitchell's quicksilver choreography. Agitation for civil rights, soon to gain powerful momentum, begins right here in the city. Sex and love, those vital ingredients without which no musical has legs, do not come in far behind.

Opening night gallery

Hairspray, now in its fifth Broadway year, sent the rare, sweet smell of success wafting through the Shaftesbury last night. Inspired by John Walters's camp, Eighties feast of a film it paints a wicked picture of blue-collar Baltimore, where girls crave their 15 minutes of fame on TV and boys crave girls. It comes at us in rare musical parts: the first part is low-camp satire and burlesque: Michael Ball deliciously fattened up and dragged down in bland frocks and lurid gowns, majestically slips into the role of the fat, foghorned laundress, Edna Turnblad, who responds to a large insult with a majestically contemptuous "Excuse me." Leanne Jones, in an astonishingly accomplished stage debut, plays Edna's big-sized daughter, Tracy, whose hair stands high as a beehive-and who hankers to become Miss Teenage Hairspray on local TV. The other part takes a radically political turn in a Baltimore where young blacks and whites cannot dance together.

It is through Jones's endearingly earnest Tracy, who dances with a lightness belying her size, that links between love, comedy and radical politicsare forged. "I just think it's stupid we can't all dance together," Tracy says and leads the picketing of the local TV station. Here Tracie Bennett's witch-like, blonde and racist producer schemes to ensure her evil daughter, Rachel Wooding's Amber, beats Tracy for the coveted Hairspray title. The book by Mark O'Donnell and Thomas Meehan may culminate in typical, glorious absurdity when Ball bursts out of a giant can of Hairspray to sing the tremendous last number,You Can't Stop The Beat, but the musical is sustained by its attack on racial discrimination and its alluring, escapist, fairytale elements. Ben James-Ellis's would-be hunk, Link Larkin, collides with Tracy and love at first sight breaks out on both sides: "We won't go all the way, but I'll go pretty far," she sings, dreaming of an imminent,erotic future. And the record shop where Johnnie Fiori's exuberant Motormouth Maybelle puts her terrific voice to good effect draws blacks and whites together.

Marc Shaiman's urgent score, with clever, often witty lyrics written with Scott Whitman, keeps Hairspray pulsating with musical excitement as well as political anger. And Leanne Jones, as smitten, adolescent lover and Miss Teenage Hairspray, effortlessly commands the stage. She will hearten all actresses who imagine that only the pencil-thin can inherit the lead dressing room.

Shaftesbury Theatre: 020 7379 5399