When he starts work in the household of Mexican artists Diego Rivera and Frida Kahlo - where the Bolshevik leader, Lev Trotsky, is also being harboured as a political exile - he inadvertently casts his lot with art, communism and revolution.

A compulsive diarist, he records and relates his colourful experiences of life with Diego Rivera, Frida Kahlo and Trotsky in the midst of the Mexican revolution. A violent upheaval sends him back to America; but political winds continue to throw him between north and south, in a plot that turns many times on the unspeakable breach - the lacuna - between truth and public presumption.