This Spanish documentary film is like many detective stories in which the manner of the search itself is far more involving than any answers it reveals. Here, the filmmakers comb the world to try to discern how Ramon Mercader came to be the murderer of exiled Russian revolutionary Leon Trotsky in 1940. Trotsky (1879-1940) was one of the original Bolshevik revolutionaries with Lenin in Russia and was a leading writer and theorist of that revolution. He served as that government's Commissar of War for six years. Trotsky had a falling-out with Lenin and was exiled in 1929. During his exile, he lived in Mexico City and continued writing. He was considered one of the main "heretics" of Russian Bolshevik Marxism, and was continually and loudly denounced by the Russian government. After bragging to friends that he would do so, Ramon Mercader stabbed Trotsky in the head with an ice pick. Mercader, who spent much of the rest of his life in prison, never revealed the planning behind his deed. On release from prison, he chose to live in Castro's Cuba, and he is believed to be buried in the Kremlin. The filmmakers traveled the world and interviewed over four dozen people in their gripping quest for answers.