This is a story about truth and how, against all the odds, it can be discerned and defended against liars through individual acts of courage and genius. It is a story for all time and particularly our time, when totalitarianism bludgeons the truth tellers with renewed support.

Pablo Picasso and George Orwell never met. But each of them, reaching the heights of their powers, looked at the same events in the same place at the same time, 80 years ago, and used their art to expose the true face of totalitarianism. At the time they were vilified for doing so.

Picasso produced his huge and wrenching masterpiece, Guernica, named for the northern Spanish city that was the first European city to be carpet-bombed. Orwell produced Homage to Catalonia, his gimlet-eyed record of fighting in the Spanish Civil War in which he nearly died.