'The Devil Wears Prada' star MERYL STREEP and former 007 PIERCE BROSNAN dance and sing for the big-screen version of the hit musical Mamma Mia!, in theaters everywhere July 18, and ET has an exclusive preview!

"It's all about dreams, hopes and happiness," says Meryl. "They just enter your body, these songs -- they have amazing hooks."

The film centers on a bride-to-be (played by AMANDA SEYFRIED of "Big Love" and "Veronica Mars" fame) in spectacular Greece who invites three men -- one of whom just may be her father -- to her wedding. Meryl plays her mother, while Pierce, COLIN FIRTH ('Bridget Jones' Diary') and STELLAN SKARSGARD ('Pirates of the Caribbean: Dead Man's Chest') play the three "dad candidates."

The film is full of classic ABBA tunes, of course, with Pierce, Meryl and company belting out songs including "Dancing Queen," "Take a Chance on Me" and "Knowing Me, Knowing You."

"Everyone's danced to Abba; everyone's been driven nuts by their songs," jokes Pierce. "The whole film has a heart to it, and I think the 'Mamma Mia!' experience has bled into this film."