This book was actually really good, even though it was really really long. It was about a bunch of kids who travel through time. I had to read parts of it a couple of times because the whole theory they have of time travel is hard to understand. The kids are used to sell products to people back in time. For example they sell a mirror to someone in medival times and make almost 10 times what they would make in modern times. Then they lose control of the time travel and they have to find their way out through friendship, instinct, and perserverance.