After finding Penny's old prom dress the girls decide to have a new prom on the roof. Sheldon is worried about the post-prom mating activities that he feels Amy will expect and has a panic attack after he sees how pretty Amy is. Amy reassures him he is under no pressure, but she does hope they will have intimacy one day. She also wants to tell Sheldon something, even if he can't say it back. Sheldon surprises her by saying he loves her. Amy is shocked, then starts having a panic attack of her own. Howard is not happy since he figures Stuart will bring his mother. Stuart embarrasses him by bringing Howard's second-cousin Jeanie, the girl Howard lost his virginity to. Howard attacks Stuart in the limo for having relationships with his family members. A jealous call from Debbie causes Stuart to abandon Jeanie at the prom. Emily reveals she loves the darker versions of fairy tales, disturbing Bernadette. Leonard and Penny dance together romantically though no music is playing. They admit that they probably wouldn't have approached each other to dance if they had met at their proms, but are happy together now.