"We're all alone and the fate of all the arcana in the entire world, as well as a lot of innocent lives, rests on whether or not we can stop a librarian from finding a butterfly..."When security consultant Zelda Pryce gets a handwritten request from the British Museum asking her to test its security, she never imagines it would lead to a chase across the Europe and Asia with a secret agent, trying to stop an elderly anarchist from creating massive, worldwide destruction. Fortunately, she has the use of her arcana - mechanical devices that bend the laws of mathematics in ways that seem magical, if not impossible.Our heroine, Zelda is a Nancy Drew-type character with "His Dark Materials" gadgets and an Artemis Fowl-like understanding of technology. A French secret agent who can warp the properties of metals, and a handsome Brit who uses mathematical probabilities to pull off heists complete the trio of "good guys" -- a daring, intelligent team who make the story interesting, and whose special talents create a world in which nearly anything is possible. Those interested in the history of science will find the names and descriptions of some of the arcana familiar -- the Archimedes Claw, the (Marie) Curie Corset, the (M.C.) Escher games, etc -- which was an intellectual treat. The story itself was intriguing, and I had a hard time putting it down!I will admit, however, that I did have a very hard time figuring out the "world" of this book. I spent a good chunk of the novel confused about the arcana, specifically:- Is Zelda's world the same as ours, and the arcana secret knowledge only known to the very elite (akin to the magic elements in Harry Potter)?- Is Zelda's world in some sort of alternate-history world in which those that can create arcana are rare, but the use of them and knowledge of them is common?- Or is Zelda's world in our not-so-distant future, a part of the progression of science?After completing the whole book, I'm leaning towards the second option, but even now I'm not entirely sure.Regardless, I'd definitely recommend this book -- though the premise of "beat the bad guys to the secret weapons that they're going to use to destroy the world" isn't new, this is a rather original take on it, one that stimulates the imagination and leaves you hoping for a sequel.Thanks to the publisher for providing me a review copy of this book!