An antique sled with amazing powers has taken Emily and Matt across the continent and all through time. They've come face to face with pirates, prospectors, the Vikings, and even dinosaurs. Now, in the seventh title in the Canadian Flyer Adventures series, they're off on their most important journey yet -- helping along the Underground Railroad, where they meet Harriet Tubman and Dr. Alexander Ross. A special section at the back of the book gives readers additional facts about the abolition movement.