On the quarterdeck of H.M.S. Pinafore, Captain Corcoran 's ship and his crew await the coming of Sir Joseph Porter, who is going to inspect Corcoran's ship and marry his daughter, Josephine. But Josephine is secretly in love with Ralph Rackstraw, a member of the crew. they attempt to elope but are apprehended. Through a strange twist revealed by Buttercup, the bumboat woman, all ends happily after all.