Aunt Harriet's under ground railroad-4 stars

Well two kids see this train up in the sky and the boy goes on the train. The sister tells him, Bebe, to get off the train but it was too late the train was already starting and the conductor is really Harriet Tubman. She tells Cassie to go on a journey if she was going to be able to see the boy again and it tells about on her journey and the letters she gets from the boy. In the book there are a lot of facts about what it was like for slaves when they escape. Cassie hears Harriet Tubman's voice telling her where to go. And at the end she finally gets to the boy. She tells Bebe to never leave her again and he says that it is more important to be free.