The Rule of Four by Ian Caldwell and Dustin Thomason is an expertly renered suspense novel filled with mystery, murder, and intrigue. The bulk of the action has an ancient manuscript at its core, one which has never been fully understood, but which could hold the secrets to one of the greatest mysteries of the Renaissance age. It is also partly a coming of age tale with the dual protagonists and best friends having to shed their youth and learn what it is to be a man on one’s own apart from the penumbra of youth and parentage. History is blended beautifully with fiction to create an amalgam that is a thrill to read. The well-drawn and compelling characters navigate to solve a five hundred year old mystery while not becoming victims in the wake of those who would see that mystery remain secret, and the truth it protects be kept forever hidden. From first-time novelists, this stunning debut is an extraordinary accomplishment.