S1·E34 Tarzan and the Gauntlet of Vengeance

Clayton's sister kidnaps Jane, Tantor, Terk, and the Professor, placing each in a separate, deadly peril. She then injects Tarzan with a fatal poison via blowdart and informs him that the antidote lies far away on a distant mountain she's dubbed "Clayton's Peak". He, therefore, has a choice—to suffer as she had and lose those he loves, or as Clayton had and lose his own life.