Summary: Samantha has a baby girl. Trouble begins for Nurse Kelton when Endora names the baby Tabatha against the parents' wishes. When Darrin doubts that the baby will grow up to look like Samantha, Endora proposes to turn the baby into a grown-up, so he can see. Darrin forbids her to do so. Meanwhile, Samantha's cousin, Serena, who resembles Samantha, visits the hospital. Shortly after, Endora carries the baby from the nursery. Darrin sees Serena and feels she resembles someone he knows. Finding the baby missing, Darrin is sure Endora's magic has been at work and Serena is his daughter, grown up. From then on, Darrin tries to return Serena to the nursery, and to get Endora to undo the harm he feels she has done.
Both witches are annoyed by Darrin's behavior. Soon they have Darrin switching from infancy to maturity, finally winding up in a straitjacket. By this time, Nurse Kelton doubts her own sanity. When the baby is returned to Samantha, Darrin convinces Nurse Kelton that his penchant for practical joking is responsible for the strange happenings. Feeling guilty at having accused Endora falsely, Darrin tells her the baby is to be named Tabatha.