For years, Wayne Simmons claimed to be a former C.I.A. operative. Then one ex-spook got suspicious. Kent Clizbe, a 55-year-old former C.I.A. officer and intelligence contractor, has cultivated a diverse set of interests in his later years. He loves bird watching and participates in his local Christmas Bird Count, an informal census organized by the Audubon Society. He has a patent on a device, the TimeOff, that prevents unattended-stove fires. But Clizbe’s true motivating force — a holdover, perhaps, from his decade with the agency — is an unrelenting compulsion to get to the bottom of things. He vets every...