Mamma Mia! 

A lot of people — OK, a lot of women — have a great reason to see Mamma Mia! How many films give actresses in their late fifties the opportunity to wear glitter platforms and dance around madly to ABBA songs? Even in musicals, such silliness is usually the prerogative of the young and nubile. But in this movie, based on the hit stage show, the ingenue and her friends actually do less giggling, squealing, gossiping, vamping and disco-ing than do the distinguished thespians playing her mother (Meryl Streep) and Mom’s two long-time pals.

The show’s book, by Catherine Johnson — who also adapted it to the screen — has just enough content to give the actors pretexts to break into 21 sugar-high hits by the Swedish pop group. Free spirit and former disco diva Donna (Streep) has one of those jobs only fictional characters seem to have, running a sleepy inn on a breathtakingly gorgeous Greek isle. Her pretty daughter Sophie (Amanda Seyfried) is about to marry a pretty boy. The only trouble in paradise is that the bride wants her dad to walk her down the aisle. Summers on Greek isles in Donna’s youth being what they were, Sophie really needs the services of a DNA lab. Undeterred, she writes to the three most likely baby-daddy candidates (Pierce Brosnan, Colin Firth and Stellan Skarsgård) and invites them to her nuptials. Still smitten with Streep after all these years, the trio shows up, driving their surprised hostess into a post-menopausal erotic tizzy. Her cronies and former bandmates (Julie Walters and Christine Baranski) encourage her to reclaim her identity as a Dancing Queen, but she isn’t sure this is the time.

That’s about as complex as the movie gets: Last summer’s Hairspray, with its kinky dose of John Waters’ humor, is Stephen Sondheim by comparison. Where other recent “jukebox” musicals such as Moulin Rouge and Across the Universe reinterpret familiar songs, Mamma Mia! simply reprises them, adding corny production numbers whose recurring motifs are frolicking Greek peasants and choruses that pop their heads over roofs or banisters to counterpoint whatever the soloist is emoting. In the Australian black comedy Muriel’s Wedding, ABBA songs were used in a way that made their guilty pleasures surprisingly poignant. Here, the script doesn’t offer any grit to contrast with the candy-floss numbers. Though some are fun, only one — Streep throwing herself the ultimate pity party with “The Winner Takes It All” — is truly memorable.

Mamma Mia! offers the limited pleasures of watching fine, mature actors behave like the teeny-boppers in High School Musical. The weird thing is, they don’t seem to mind. The scene where Pierce Brosnan belts out “SOS” has camp classic written all over it, because the former James Bond gives it his all, rusty pipes be damned. Though Firth seems a little embarrassed, the other actors attack their roles and songs with the same conviction.

That includes Streep — though, luckily, she can sing. She’s broad, rollicking and uninhibited here as a lusty dame, as are musical theater veterans Walters (Educating Rita) and Baranski, who co-starred in “Cybill,” American TV’s ripoff of the U.K. sitcom “Absolutely Fabulous.”

That’s worth noting not just because Baranski plays essentially the same rich-bitch character here, but because “Ab Fab” was the first and best comedy to celebrate the phenomenon of women of a certain age behaving badly. Jennifer Saunders’ show redeemed its campiness with hyper-articulate, rapid-fire dialogue that puts “Sex and the City” scripts to shame. Mamma Mia! seems to be striving for the same level of antic naughtiness, but lines such as “Why Donna Sheridan, you shady lady!” just don’t bring it.

As a result, the performer who comes out of this mess looking the best is saucer-eyed Seyfried, who’s maniacally cute in her Sweet Young Thing role. The other actors evoke a few too many memories of wasted wedding guests singing along to ABBA tunes, which is more fun when you share their sauced condition. Young at heart is one thing. Dumb at heart is another.