On August 21, 1940, Trotsky was assassinated in Mexico City, after eleven years of exile. The killer, Ramon Mercader, a young Spanish communist, was a character straight out of a spy movie. He was recruited in 1937 by Stalin's secret service when the latter decided to eliminate Trotsky, that tireless opponent. Through the epic story of Trotsky's last years in exile in Mexico, enriched with flashbacks to his political past, this film, a true historical thriller, offers a cross-narrative between Trotsky's life in exile and the setting up, at the same time, of "Operation Duck", the code name for his assassination.