The Prince swears he will marry the girl to whom the lost glass slipper belongs. Elated, the King sends the Grand Duke to try it on every maiden in the country. When word of this reaches Lady Tremaine's chateau, the two stepsisters immediately order Cinderella to get them ready. Lady Tremaine overhears Cinderella humming the waltz from the ball; realizing Cinderella is the 'mystery girl', she locks Cinderella in the attic while Anastasia and Drizella try on the slipper. Jaq and Gus steal the key and try to get it back to Cinderella, but are stopped by Lucifer. The birds summon Bruno, who chases Lucifer until he falls out a window, and the mice free Cinderella just as the Grand Duke is about to leave.