"GREY'S ANATOMY - ""Walk on Water"" - Beginning February 8, Grey's Anatomy enters a three-episode story arc that will challenge the interns of Seattle Grace -- and ""Grey's"" fans as well -- like never before. ""Walk on Water"" airs THURSDAY, FEBRUARY 8 (9:00-10:00 p.m., ET) on the ABC Television Network. Elizabeth Reaser (Independent Spirit Award winner for ""Sweet Land"") guest stars as a patient over multiple episodes. (ABC/VIVIAN ZINK)JAMES PICKENS, JR., SARA RAMIREZ, KATHERINE HEIGL, ELLEN POMPEO, CHANDRA WILSON, SANDRA OH, KALI ROCHA"