seems that most reviewers loved this book. It IS an interesting premise..so you have to buy into the time travel/magic concepts I suggest reading the other reviews..there are pros / cons. I'm glad I read it but found it hard to follow it due to being told in so many different ways: Journals, power point presentations, memos, etc

Tristan needs Mel to translate some very old documents, which, if authentic, are earth-shattering. They prove that magic actually existed and was practiced for centuries. But the arrival of the scientific revolution and the Age of Enlightenment weakened its power and endangered its practitioners. Magic stopped working altogether in 1851, at the time of the Great Exhibition at London’s Crystal Palace—the world’s fair celebrating the rise of industrial technology and commerce. Something about the modern world "jams" the "frequencies" used by magic, and it’s up to Tristan to find out why.

And so the Department of Diachronic Operations—D.O.D.O. —gets cracking on its real mission: to develop a device that can bring magic back, and send Diachronic Operatives back in time to keep it alive . . . and meddle with a little history at the same time. But while Tristan and his expanding operation master the science and build the technology, they overlook the mercurial—and treacherous—nature of the human heart.