Smitten by Larry Tate, Samantha's lookalike cousin Serena slips Larry a pill which makes him progressively younger. Astonished at his rejuvenation, Larry tries to talk Darrin into marketing the pill, little realizing that the side effects would transform the nation's male population into children. Ted Foulkes and David Hayward play the younger versions of Larry Tate (David White). Written by Michael Morris, "Serena's Youth Pill" first aired on February 5, 1972. ~ Hal Erickson, Rovi