Luka, Abby, Morris, and the team treat the victims of a collision between a big-rig and a family car, including the wife of the truck driver and the son of the car's driver. Sam celebrates her birthday in the ER and meets a photographer who changes her outlook on life. Neela and Ray share some subtle signals. A medical student shadows Gates. Wedding plans continue as Luka and Abby try to decide where to be married and how to cope with a too-helpful Morris and Hope.

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.