Sunny as its Greek island locations and its attitude, "Mamma Mia!" earns its exclamation point. The adaptation of the long-running stage hit is a crowd-pleasing gusher of escapism, not the least of which is respite from summertime teen action fare. How refreshing to find a cast in their 50s kicking up their heels, belting out corny Europop and reveling in every campy moment. The ABBA songbook gives me hives, but in a context this joyous, there's no resisting it.

Meryl Streep plays Donna, a onetime singer/single mom who runs a B&B on the Greek island of Kalokairi with her 20-year-old daughter, Sophie (Amanda Seyfried of HBO's "Big Love"). Sophie, who has never known her father, searches Donna's diary for clues and learns of three men who might qualify.

As her wedding day approaches, she secretly mails invitations from Donna to New York businessman Sam (Pierce Brosnan), London banker Harry (Colin Firth) and globetrotting adventurer Bill (Stellan Skarsgård). The men, strangers to one another and unaware that they might have fathered Sophie, mix it up with Donna and her free-spirited friends (Christine Baranski and Julie Walters), and multiple romantic crossroads are crossed. Square ABBA songs are repeatedly pounded into round plot holes.

The setup is frankly weak, and there's not much wit in the dialogue. It's the cast's willingness to take the silly material and run with it that makes the whole thing work. Believe it: This is a celebration of musical exhilaration, not a case of well-known actors slumming for a check.

Streep is a natural actress and a talented singer. When she tears into "The Winner Takes It All," you feel as if you're looking past the song and experiencing the actual life of her warm, vulnerable, womanly character. Her co-stars labor a bit harder to sell their characters and the ABBA tunes. Brosnan sing-speaks his songs so awkwardly that my companion asked, "Is this supposed to be funny?" "Probably," I said.

Even when the film has the farcical feel of movie stars' karaoke night, its sense of fun is infectious. The dance scenes are edited in rapid bursts of movement, no shot lasting more than a couple of seconds, so the stars don't get out of sync with the sure-footed chorus.

But there are clever ideas on display. One scene puts a squad of dancers in swimsuits and flippers, prancing like a flock of high-spirited ducks. Walters and Skarsgård sing "Take a Chance on Me" as they crawl along perilous rooftops, and the finale puts the cast in Kiss-style monster boots and spangled jumpsuits for a blissful curtain call.

"Mamma Mia!" is uneven, as such jukebox movies inevitably are, but at its best moments, it could reduce even a hardened movie critic to helpless laughter.

Colin Covert • 612-673-7186