Voodoo Histories by David Aaronovitch (Riverhead, 402 pages, $16).

Subtitled "The Role of the Conspiracy Theory in Shaping Modern History," journalist Aaronovitch's book asks why many folks believe odd, incredibly complicated explanations for some events. He tackles conspiracy theories such as: the secret Zionist world empire; 9/11 was an inside job; the moon landings were faked; Princess Diana was murdered; Freemasons run the world; Obama is not a U.S. citizen; FDR knew about the Pearl Harbor attacks in advance and did nothing; or the Priory of Scion's mission to safeguard the bloodline of Jesus.

This is lively, entertaining, and intelligent reporting in which the author looks at reasons why intricate, convoluted theories attract so many believers when simpler, much more plausible answers are readily available. Aaronovitch says it's a combination of gullibility, a lack of critical reasoning skills, and the inability to tell the difference between the possible and the barely plausible.

Aaronovitch's tone is evenhanded, but he doesn't cut any slack for purveyors of some theories. Here, for example, is his take on those who say the Pentagon wasn't hit on 9/11 by terrorist-piloted American Airlines Flight 77: "There is always the possibility, however extraordinarily remote, that DNA might have been planted to the exact specifications of the missing passengers, crew and employees, that wreckage might somehow have been placed at the scene within minutes of the crash, and that the real occupants of the missing Flight 77 might have been spirited away to some unknown place, there to be butchered or to live in the world's weirdest witness protection program."