Darkness at Noon is one of the great political novels of the twentieth century: cold, claustrophobic, and still nasty in all the right ways.

Koestler follows Rubashov, an ageing revolutionary imprisoned by the regime he once helped build, as he is interrogated, broken down, and forced to confront the logic of ideology taken to its terminal end. 

The novel is rooted in the Great Purge and Moscow show trials, but Koestler keeps the setting slightly abstract, which gives the whole thing a more general and sinister force: this is a book about confession, power, moral compromise, and the machinery of belief when it starts eating its own children.

Penguin Modern Classics paperback, reissued 1964, reprinted 1965. A nice Penguin Modern Classics copy in good condition.