How did so many promising men in government wind up dead before their time, by such variously violent means? But it’s also a whodunit to rival anything by Agatha Christie. “Secret City,” by James Kirchick, is a sprawling and enthralling history of how the gay subculture in Washington, D.C., long in shadow, emerged into the klieg lights. SECRET CITY The Hidden History of Gay Washington By James Kirchick 826 pages.