One of the hazards of working in a profession is complacency; over the years, it can be easy to miss the obvious. When Walter Kirn — a widely published author of novels, essays and reportage and an all-around observer of humanity — met Clark Rockefeller, he missed the obvious, something Kirn slowly comes to understand in his gripping new memoir/true crime book, "Blood Will Out."

Kirn met Rockefeller in 1998, when Kirn — doing a favor for a friend of a friend — agreed to transport a small, disabled dog across the country and deliver it to Rockefeller, who had adopted the dog over the Internet.

Kirn agreed to do it for the friendship, for the money — and for the enticing opportunity to meet a Rockefeller.

Rockefeller — let's just go on calling him that for a minute — was wealthy, eccentric and worldly, and the two men formed a strange friendship. Kirn was aware that it was an unusual, sometimes one-sided relationship, with Rockefeller treating Kirn more like a sounding board than a friend, more of an audience than a kindred spirit. When Kirn found himself held at arm's length from his "friend," he chalked it up to eccentricity, the stilted relational dynamics of the wealthy with the commoner.

"Blood Will Out" isn't written as a "shocking twist at the end" type of book, so it's acceptable to reveal that Clark Rockefeller wasn't a Rockefeller at all. His real name was Christian Gerhartsreiter, and he was an extremely gifted grifter, a con man who had built multiple identities and lives out of elaborate lies.

Gerhartsreiter had carried out an extraordinary charade, one that depended on his charm, his intellect and the elimination of anyone he perceived as blocking his way.

"Blood Will Out," by Walter Kirn

Kirn bounces back and forth through the years, laying bare his own blind eye while dissecting how two people can come to know each other so well and, simultaneously, not at all. "Blood Will Out" combines elements of "In Cold Blood," "The Talented Mr. Ripley" and any number of sordid tales of grift.

Where it stands out is in Kirn's unflinching perspective, willing to uncover the myriad ways he enabled the con to go on for so long. It's a bracing, engrossing read by a writer who has finally cast aside the blinders.

Matthew Tiffany is a writer and psychotherapist.