Series 12 Episode 13

S12 E13: When an abandoned patient with Amyotrophic Lateral Sclerosis arrives at the emergency room, many of the doctors are shocked to recognise former medical school professor Dr Nate. Abby and Kovac try to understand Nate's wishes after the professor is struck with pneumonia in addition to the nerve degenerating disease, and as the malady continues to cripple Nate, Abby struggles with the prospect of losing the man who made her a doctor.