Fiction about the nation’s capital is a growth that flourishes only on the lower slopes of Parnassus. Think of the flower of our novelists—Updike, Mailer, Roth, Cheever, Bellow—and see if you can call to mind a single scene that is set on the banks of the Potomac. Mailer did a famous nonfiction account of the march on the Pentagon (The Armies of the Night), and Updike briefly created a lifelike President Buchanan, but that second exception proves a more general rule, exemplified by Gore Vidal’s canon: historical reconstruction is the form in which our novelists prefer to approach the matter....