In 1906, the western states of America suffer a string of bank robberies by a single man who then cold-bloodedly murders any and all witnesses, and vanishes without a trace. Fed up by the depredations of The Butcher Bandit, the U.S. government brings in the best man it can find: a tall, lean, no-nonsense detective named Isaac Bell, who has caught thieves and killers from coast to coast.

But Bell has never had a challenge like this one. From Arizona to Colorado to the streets of San Francisco during its calamitous earthquake and fire, he pursues a fiend who seems to draw pleasure from the challenge and a woman who may to hold the key to the man's identity. As Bell begins to suspect a new term used among top psychologists, sociopath, may describe his target, the Butcher Bandit turns the chase around on him. The hunter becomes the hunted. And soon, it will take all of Bell's skills not merely to prevail . . . but to survive.

In 1911, in Colorado, Isaac Bell is asked to look into an unexplained tragedy at Little Angel Mine, in which nine people died. His dangerous quest to answer the riddle leads to a larger puzzle centered on byzanium, a rare element with extraordinary powers and of virtually incalculable value. As he discovers that there are people who will do anything to control the substance, Isaac Bell will find out just how far he'll go to stop them.