In the overburdened emergency room of the urban Chicago teaching facility County General Hospital, a Level One Trauma Center, the difference between life and death rests on split-second decisions -- and the pressure, joy and guilt are often overwhelming. On staff are Dr. Abby Lockhart who made the professional transition from nurse to doctor and is making a serious effort to turn her personal life around; Dr. Gregory Pratt now an attending, whose checkered background won't stop haunting him.