John O’Neill is the unlikely author of an unlikely story.

O’Neill, a 1967 graduate of the U.S. Naval Academy and an oil and gas litigator from Houston, swore off writing after publishing “Unfit for Command: Swift Boat Veterans Speak Out Against John Kerry” (Regnery Publishing, $27.95). But a visit to the Vatican intrigued him so much that he embarked on “The Fisherman’s Tomb: The True Story of the Vatican’s Secret Search” (OSV, $21.95), an account of the clandestine quest to find the bones of St. Peter. It’s a tale that recalls “Indiana Jones” or “The Da Vinci Code,” complete with mistakes, red herrings and bureaucratic back-stabbing, redeemed by a large measure of faith — and unlike those works of fiction, it’s all true.