Sapphire & Steel (1979)

Season 2: Episode 4

Steel continues to taunt the ghost of the solider but pauses when he finds Sapphire and Tully unconscious. A hallway in the railway station has become a re-creation of a submarine where three young men died from lack of oxygen. Sapphire and Tully nearly suffocate but Steel manages to carry them to safety before the three of them meet the same fate as the young submariners. Afterward, Sapphire and Steel agree to give Tully's methods a chance by holding a séance to find more information about the solider when he was alive.