In 1937, in one of the worst civilian casualties of the Spanish Civil War, Fascist forces bombed the village of Guernica in Northern Spain. For Pablo Picasso, the tragedy sparked a frenzied period of work in which he produced a massive anti-war mural, titled "Guernica." How can we make sense of this overwhelming image, and what makes it a masterpiece of anti-war art? Iseult Gillespie investigates. [Directed by Avi Ofer, narrated by Adrian Dannatt, music by Marcos Tawil].