In only 12 hours, a pressured Luka must coordinate the emergency closure of the ER, and the team rallies to make provisions for patients. Chaz is admitted to the ER, worrying Pratt, and Ray is challenged by a young patient. Sam renews her friendship with the photographer Diana, while Gates faces new problems on the father front. At day's end, as the lights go out, Luka makes a pivotal decision about his future.