The family has noticed that Wally has been spending much time of late at Cindy Andrews' house, she who is supposedly Eddie's girlfriend. Wally doesn't say what he is doing with Cindy, he seemingly reluctant to do so, and Ward and June don't want to pry. They just hope that what appears on the surface - that he is moving in on Eddie's girl, while Wally is still supposedly dating Julie Foster - is not the case. In reality, Wally is acting as a live mannequin for Cindy, who is knitting a sweater for Eddie as a surprise for his birthday. Things quickly start to get out of hand with Wally and Cindy's secret as Beaver, without telling Wally that he did so, inadvertently tells Julie that Wally is over at Cindy's, and Lumpy overhears Cindy and Wally making a "date", which Lumpy spreads to Eddie. Eddie and Lumpy even catch Wally sneaking into Cindy's house one evening. With all these issues transpiring, Wally has to decide what to do to keep Cindy's surprise still a surprise from Eddie, retain his friendship with Eddie, and not lose Julie as a girlfriend.
—Huggo