Human nature is stranger than anything. It was never more so than with Gary Hart, the Kansas boy from the ultra-strict Nazarene background who went Hollywood in 1972 in the presidential campaign of George S. McGovern.

Hart’s own campaign for president, based on his claim to distilled ideas and pure public conduct, collapsed 15 years later when he posed near the pleasure boat Monkey Business with blonde Donna Rice on his lap. As a pure human puzzle he ranks with the greats, and Matt Bai’s new book — All The Truth Is Out — is one of the better ones about him. It is fair, comprehensive, and very well written, but marred by two flaws: