GREY'S ANATOMY - "Song Beneath the Song" - In a series first, the music that has been at the heart of the show and been beloved by fans comes to life for Grey's Anatomy: The Music Event. A cataclysmic event rattles the doctors of Seattle Grace to the core, as Callie, on the verge of an enormous life-changing moment with Arizona, envisions her hospital and friends as it has never-been-seen before. "Chasing Cars" (Snow Patrol), "How to Save a Life" (The Fray) and "The Story" (Brandi Carlile) are among the songs performed by the cast in one of the most special hours of "Greys Anatomy" yet, THURSDAY, MARCH 31 (9:00-10:01 p.m., ET) on the ABC Television Network. (ABC/RON TOM) JESSICA CAPSHAW, SARA RAMIREZ