If last season's bullet-riddled Grey's Anatomy finale didn't teach you that lives can change in a heartbeat, get ready for another harrowing reminder - with a whimsical twist!

So says TV Guide in a new story on the show's upcoming musical episode, which centers on a crisis involving five-months pregnant Callie and a look inside the doctor's mind.

It's a clever device that allows most of the cast - plus Private Practice's Kate Walsh - to break into song in an episode unlike any the show has attempted to date.

"There were cast members who had some trepidation about it," says Tony Phelan, who directed the much-hyped March 31 episode. "But they all dove into it."

Especially Ramirez.

"It's like a dream I didn't even know I had coming true," says the actress, who won a 2005 Tony Award for her Broadway run in Monty Python's Spamalot.

"It feels like everything in my life and career has been leading up to this moment."

While the details of Callie's ordeal are being kept mostly under wraps, Ramirez reveals to the TV magazine that her character experiences "a life-altering event that [allows her] to process why her life with Arizona is worth fighting for."

So, at hour's end, will the doctors paying tribute to the music of Grey's be singing lullabies or the blues? Ramirez advises coming prepared for either scenario.

"Have a Kleenex nearby," she says. "Just in case it gets to be too much."

Here's a scan of TV Guide's article on the episode ...

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.