S4·E14 Tunnel of Fear

While traveling alone in a train compartment, an elderly, wealthy, wheelchair-bound man (Cedric Hardwicke) is confronted by a younger man (David Niven), whom he had double-crossed over twenty years ago. The younger man, now bent on revenge, tells the elderly man that he intends to kill him when the train passes through an upcoming tunnel. A battle of wits ensues.