In the summer of 1998, Walter Kirn set out to personally deliver a crippled hunting dog from his home in Montana to the New York apartment of Clark Rockefeller, a secretive young banker and art collector who had adopted the dog over the Internet. Thus began a 15-year relationship that drew Kirn deep into the fun-house world of an outlandish, eccentric son of privilege who ultimately would be unmasked as a brazen serial impostor, child kidnapper and brutal murderer.