Sara Ramirez Sara Ramirez

Gotta admit, when I first heard ABC's Grey's Anatomy was staging a musical episode, I had serious doubts about what Patrick Dempsey (Derek) jokingly refers to as "Glee M.D." And I wasn't the only one.

"Ellen Pompeo [Meredith] was very much like, 'Tell me we're not going to sing and dance in the hall. This is crazy!'" recalls creator Shonda Rhimes, who dreamed up the risky concept as a love letter to fans. But after the cast's first script read-through, Rhimes says Ellen "came up to me and said, 'I never say I'm wrong, but I was wrong and I want to sing more!' She's having so much fun with it."

I'm sold, too, after a visit to the set to hear the cast's full soundtrack — just wait until you hear Chyler Leigh's Lexie croon Anna Nalick's "Breathe (2AM)" — and see how the songs are used to orchestrate a crisis involving pregnant Callie (Sara Ramirez). The hour, which airs March 31, takes us back to the much-beloved early seasons of Grey's, when music played a vital role on the show. Rhimes says the songs selected "are the ones most associated with the show and make me think of the scenes they [originally] played in."

For instance: Snow Patrol's "Chasing Cars," recorded for this episode by Sara, Kevin McKidd (Owen) and Chandra Wilson (Bailey), and Kate Havnevik's "Grace" (sung by Sara and the female cast) were first heard during the Season 2 finale "when Meredith and Derek had sex during the prom, Denny died and Izzie quit," says Rhimes, who next hopes to showcase Taye Diggs' talent with a musical Private Practice.     

And anyone remember the abandoned Grey's theme song, Psapp's haunting "Cosy in the Rocket"? (Sample lyric: "Nobody knows where they might end up; nobody knows...") "It's used in this episode in a really interesting way," says Sara, who won a Tony Award in 2005 for Broadway's Monty Python's Spamalot. "Not at all how you might expect."

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