Gilbert & Sullivan's H.M.S. Pinafore opens with the crew of the Pinafore busily and boisterously sprucing up the deck for the arrival of Sir Joseph Porter, a high-ranking admiral. They pause only to buy wares from the peddler called Little Buttercup and then return happily to work. But not all are so happy. Ralph Rackstraw, "the smartest lad in all the fleet," is in love with the Captain's daughter, Josephine, who has been promised to Porter. In spite of this -- and the fact that Josephine and he are far apart in terms of class -- Ralph pursues her, and she eventually confesses her own love for him. The two young lovers plan to elope, but the Captain learns of her plans and puts a halt to them. Porter, furious at Ralph's impertinence, has him imprisoned. At that moment, Buttercup reveals a tremendous secret: Many years in the past, she had been given charge of two babies, one of good family and one of lower status. These turn out to be Ralph and the Captain -- but Buttercup further reveals that she had accidentally switched them. Thus, Ralph is of noble birth and the Captain comes from poverty -- and therefore, Josephine is also of the lower class and no longer a fit mate for Porter. However, the newly-ennobled Ralph has no such reservations, and gladly takes Josephine to be his wife. ~ Craig Butler, Rovi