Exclusive: Mandy Moore to Guest-Star in Grey's Anatomy Finale

Mandy Moore will be checking into Seattle Grace for the two-hour finale of ABC's Grey's Anatomy, TVGuide.com has learned exclusively.

The 25-year-old singer-actress (A Walk to Remember) will play Mary, a patient being treated by Bailey (Chandra Wilson) in the May 20 finale.

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Sources said Moore is just one part of the kind of finale that executive producer Shonda Rhimes loves keeping under wraps, so no further details on her role were released.