Summary: Darrin quarrels with Samantha's cousin Serena, who is her double. Serena, now the hippiest of hippies, sings rock and roll lullabies to Tabatha. Then she causes a riot at a park love-in and is arrested. Samantha zaps the picture out of Darrin's paper. However, Larry and Louise Tate think it is Samantha. Louise feels it might be Serena but Larry worries the bad publicity will cost him the Giddings Tractor account because Giddings is an old-fashioned farmer at heart. At the Stephens' that night, the Tates see Serena's psychedelic guitar and a telecast that she has vanished from jail. Darrin explains she is Samantha's cousin but Larry is still skeptical.
Serena, coming to apologize, hears Darrin speak unkindly of her. Bent on revenge, Serena, in full hippie regalia, shakes up Darrin's office by pretending she is Samantha. To convince Larry, Darrin invites the Tates to see Serena and Samantha at the same time. Unable to summon Serena, Samantha zips back and forth from Serena's identity to her own. With the table set for five, Darrin admits defeat and is sorry he started with Serena. Appeased, she appears and Larry sees Serena and Samantha together. Later, Giddings is won over by Samantha's home baked bread and Serena's resolve to reform.