After the first 2 books I was really excited to start this one. But it just kept falling flat. It took too much of the book for characters to explain what is happening. The main characters are in the dark the entire book, and keep saying "Well at least that is one thing that makes sense." I felt the same way. The plot tries to be too inticate and clever, and falls flat.
The first two were good old timetravel adventure, this one tries to be a spy novel. It is OK, but really does not measure up to the others, I hope the next one is better.