Orion and her brother Ollie think it's just a funny, old mirror, until they see the reflection of a girl who isn't really there. Not only that, she looks like somebody from another time. With neighbors Sal and Sofi Martelli, they learn the story of Susanna Chase, who escaped from slavery on the Underground Railroad in 1860. Susanna was waiting for her father to run away from his master and go with her to Canada, but she died of the measles before he could meet up with her. She never knew if he got away, and she can't "die satisfied" until she finds out. The kids seek help from Granny, who reveals a long-buried secret. A diary, a doll and a harmonica lead them to answers for Susanna, but they're almost out of time-they have to tell her before she goes back to her grave forever! The bonus? An amazing connection that nobody expected.