Born in the United States, reared in a series of provisional households in Mexico—from a coastal island jungle to 1930s Mexico City—Harrison Shepherd finds precarious shelter but no sense of home on his thrilling odyssey. Life is whatever he learns from housekeepers who put him to work in the kitchen, errands he runs in the streets, and one fateful day, by mixing plaster for famed Mexican muralist Diego Rivera. He discovers a passion for Aztec history and meets the exotic, imperious artist Frida Kahlo, who will become his lifelong friend. When he goes to work for Lev Trotsky, an exiled political leader fighting for his life, Shepherd inadvertently casts his lot with art and revolution, newspaper headlines and howling gossip, and a risk of terrible violence.
Meanwhile, to the north, the United States will soon be caught up in the internationalist goodwill of World War II. There in the land of his birth, Shepherd believes he might remake himself in America's hopeful image and claim a voice of his own. He finds support from an unlikely kindred soul, his stenographer, Mrs. Brown, who will be far more valuable to her employer than he could ever know. Through darkening years, political winds continue to toss him between north and south in a plot that turns many times on the unspeakable breach—the lacuna—between truth and public presumption.