What begins to pursue the coach on the journey to the girls' finishing school? How do they escape?

On the journey to the girls' finishing school, the coachmen sound the alarm that the coach is being followed by a group of ogres. Under the influence of the sound of the ogre's persuasive voices the coachman slows the coach down until someone gets the idea to drown out the sound of their voices. Everyone begins to scream - Olive being the most effective screamer - and they leave the ogres far behind.