Koestler's world-famous novel about the former people's commissar Rubashov, who falls victim to the political purges within his own revolutionary party and is brought down in merciless interrogations, alludes to the Stalinist show trials of the 1930s and exposes the mechanisms of totalitarian and dictatorial systems. The novel was written in 1939 in France. The translation made by Koestler's then partner (which was partially inadequate) reached the London publisher just in time before the German invasion of Paris; however, the original German manuscript was lost. Koestler later translated his own novel back into German based on the English edition. In 2015, the Kassel Germanist Matthias Wessel caused an international stir when he discovered the lost original in a Zurich library.