In the first episode of a two-part story, Burke (Isaiah Washington) orders a "Code Black" when a WW2 re-enactor is brought in with a homemade bomb embedded in his chest. There's tension aplenty as the man is brought into surgery while young paramedic Hanna Davies (guest star Cristina Ricci) nervously holds the explosive in place and bomb-squad detective Dylan Young (Kyle Chandler) tries to maintain order and calm. Elsewhere, Alex (Justin Chambers) and Izzie (Katherine Heigl) undergo life-altering experiences that neither could ever have dreamed of; and Bailey (Chandra Wilson) finally goes into labor--while her husband is nowhere to be found. ~ Hal Erickson, Rovi