The Lacuna purports to be the journals (with some samples of correspondence, newspaper clippings, and some chapters of fictitious editorial explanation) of Harrison Shepherd. Teenaged child of feckless/indifferent parents, living with his mother in Mexico, Harrison by chance becomes plaster-mixer and then factotum for Diego Rivera, which brings him into association with Frida Kahlo, and in turn with the exiled Leon Trotsky, whose secretary he becomes.
After Trotsky's assassination, Harrison moves to Asheville, NC, where he writes a series of successful popular historical novels on Mexican themes, with possible allegorical intentions reflecting on American politics of the 1940s. In the McCarthy era, however, Harrison gets labelled a fellow traveler and falls from the public's favor, making his complicated life--he's a closeted gay man--even more complicated.
Seeing that the United States' relations with Mexico, Rivera's relations with Kahlo, Trotsky's relations with Stalin, McCarthyism, and the closet are all topics with lots of potential for venting conventionally enlightened and righteous opinions, I was a little worried, but Kingsolver's instincts as a novelist are too sure-footed, her politics too canny, her humanity too genuine for this to turn into the bloviating fest it could all too easily have become.
And the theme of the lacuna--in the first place, a lagoon in Mexico that comes to figure as the heart of Harrison's secret, but then the sign of any number of gaps, omissions, erasures: what the 1930s left really had been before it was demonized by McCarthy, what history includes and excludes, what people looking at paintings see and fail to see, what the life of a pre-Stonewall gay man was likely to be--gives the novel, compelling enough for its plot and characters, a whole other kind of strength.
Harrison's novels, set in ancient Mexico, are in some sense about the 1940s, and The Lacuna, set in the middle decades of the 20th century, is in some sense about the first decade of the 21st, when fear, incomprehension, and denial were again the fuel of politics as they were in the years immediately after WW II.