I can't recommend this book as it's basically a re-hash of media articles about Keyes' capture and interrogations while he was in federal custody awaiting trial for the murder of a young woman working at a coffee stand in Alaska. There should not be any spoilers here, but if you don't know anything about Keyes at all, this book will only give you a fantasy story, not fact. The investigations into Keyes' criminality is ongoing and it is too early to write "the true story" of him at this point. The book's introductory scenes and other scenes where Keyes is depicted committing crimes are purely speculative and, frankly, done better by fiction writers.
During interrogations Keyes bragged that he had killed many people around the US, as well as committed bank robberies and arson. He tried to fool his interrogators and string them along as much as he could without actually revealing much detail about any crimes, but was forced to admit to the murder of a couple in Vermont. His testimony about that murder, however, was contradictory over several days and is probably not the whole story, or even the real story, of how or why he chose this particular couple, who lived on the other side of the country from his home. Keyes committed suicide before the FBI could get more out of him, but investigations continue. I think there is much more coming, and a better writer to bring it to us.