After suffering an explosion at the hands of a terrorist bomber he's been tracking, detective Ben Walls awakens in a hospital surprisingly uninjured and ready to go back into the field. But at the behest of his Captain and the hospital's few but eerily incongruous patients and staff, Ben is forced to remain inside the building. As Ben navigates the hospital's alarmingly empty hallways, he soon finds himself hunted by a self-proclaimed avenging angel who may be the terrorist he's been looking for, and haunted by apparitions whose deadly motives remain a mystery. As Ben's sense of reality begins to spiral out of control and the demons that surround him close in, he must find a way to both stop the supernatural forces that want him dead and catch the bomber before he strikes again.