“The United States claims to be a nation founded on an idea,” writes Theodore R. Johnson, “but Americans—even though we nod our heads to that assertion—do not agree on what that idea is, what it should do, or who it is for.” The reality is that America is facing an existential quandary. Its citizens...

Who could predict that a British aristocrat would so energize American antifascist and civil rights struggles that Time magazine would crown her “Queen of the Muckrakers”? Jessica Mitford, always known as Decca, was brought up by an eccentric English family to marry well and reproduce her wealth and...