Summary: Samantha summons Serena to babysit while she and Darrin attend a charity luncheon. Serena comes over in a bikini as Sam has zapped her off the beach in St. Tropez. When Sam leaves, Serena goes out to the patio to continue her sun bathing. Larry comes over to return Darrin's putter and Serena flirts with him. She convinces him to take a pill that will make him younger. Larry leaves the house in a hurry, before he gets into trouble and when he walks into his own house, his wife Louise looks at him in surprise. He passes a mirror and sees that his once gray hair and mustache are now a bright red, his walk is jauntier and his attitude younger.
Later, Larry visits Sam and Darrin and tells them he wants to market the fabulous pill that has made him feel and look so young. They make excuses and say NO! Sam is very worried because the pill makes one younger and younger and younger. She tells Serena to find the antidote before Larry starts slipping back. Louise comes over to tell the Stephens how worried she is about Larry's sudden rejuvenation. Darrin goes to the office and sees that Larry has already gone back ten years. Sam comes over and Larry is now an 18 year old boy. As Sam and Darrin take him back to their house Larry becomes 10. Serena is there with the antidote and in a few minutes Larry is back to his old gray self -- much to the relief of everyone.