Darkness at Noon
(First edition: London: Jonathan Cape 1940)

Darkness at noon made Koestler's break with the Communist Party explicit and by the way marked his success, establishing his fame as a political writer and as a novelist.

The book, that Burgess considered to be the archetype of the political novel, was judged in 1999 to rank at the 8th place in the 20th century list of best books.

The main character of the book, Rubashov, is an old Bolshevik that, after having struggled for the Revolution, having worked for the Communist Party in Germany and having imprisoned by the Gestapo, falls victim in Stalin's great Purge.

Rubashov's meditations in his cell lead him to recognize that all too often he sacrificed his ethic principles for the sake of the Revolution, ignoring the conflict between ends and means that has crossed his life. After long questioning by the GPU he decides that now his turn has come, and that he must be sacrificed in order to strengthen the Soviet State. He therefore confesses having conspired to assassinate the Party's n. 1, (Stalin) and is executed.

Also, Darkness at Noon was Koestler's answer to a question that had been troubling his life (and the life of the European Left) in the last few years: how was it possible that Bucharin and other heroes of the Revolution, tried for conspiracy against the USSR, publicly confessed the most incredible crimes like conspiring against Stalin's life on behalf of the Gestapo and trying to overturn the Soviet Union by means of a counter-revolution. After the executions resulted from the show-trials held in Moscow in 1936-1938 Stalin was the only survivor of the first generation (the Old guard) of revolutionaries.

The novel, apart being inspired by the Moscow show trials, was also an offspring of the news that Koestler had of his friend Alex Weissberg, a friend of his living in Kharkov that for three years was in the GPU prisons under similar circumstances. Weissberg, later set free, recalled his experiences in The conspiracy of silence.

The Gladiators, Darkness at Noon, and Arrival and Departure were make up a trilogy about the problem of ethics in politics.