This is one the great works of anti-Stalinist literature. It is an attempt by the ex-Communist Koestler to imagine how Soviet interrogators squeezed confessions out of men like Zinoviev, Kamenev and Bukharin — men who had led the revolution and had themselves in many cases stood up bravely to torture and imprisonment under the tsarist regime. And yet to a man, it seemed as if they all confessed during the Moscow show trials to crimes against a revolution to which they had dedicated their lives.
This book is above all a work of imagination; Koestler could not have known what was discussed between prisoners and their NKVD torturers. He guessed that at least in some cases, the accused were actually persuaded by the logic of doing one last service for the Communist Party. He may have been right.
The protagonist, Rubashov, is a sympathetic character, introspective and thoughtful. And yet he realises his own guilt in creating the system that is about to destroy him. He has been forced by it to lie and betray, and aware of his guilt he is prepared to sign confessions admitting to crimes he could not have committed. He knows that he committed other crimes, and deserves to be punished for those.
Essential reading for anyone who wants to understand totalitarianism, especially in its Bolshevik variant.