In the second to last book of the original series, we get a history lesson. A little bit on where the keys came from, and even more importantly, what happen in the past to the kids dad. The kids found the Clockwork keys, that when used, allows them to travel back into the past. The nice thing, is that while they may spend days in the past, it is only seconds in their time. To say any more gives too much away. But it’s good. How good….. Read it to find out.