S12, E13: When an abandoned patient with Amyotrophic Lateral Sclerosis (ALS or Lou Gehrig's Disease) arrives at the emergency room, many of the doctors are shocked to recognize former medical school professor Dr. Nate Lennox (James Woods - "Salvador," "Ghost of Mississippi," "Be Cool"). Abby and Kovac try to understand Nate's wishes after the professor is struck with pneumonia in addition to the nerve degenerating disease. As the malady continues to cripple Nate, Abby struggles with the prospect of losing the man who made her a doctor. After a controversial decision to help Nate breathe, Abby and Nate's caretaker, Fran (Ally Walker - "Profiler"), wonder if they made the right decision.