From the Amazon link:
Arthur Koestler (1905-1983) was a Hungarian-British author and journalist who immersed himself in the major ideological and social conflicts of his time. In 1931 Koestler joined the Communist Party of Germany until, disillusioned by Stalinism, he resigned in 1938. In 1940 he published his novel Darkness at Noon, an anti-totalitarian work that gained him international fame. Over the course of his life, Koestler espoused many political causes. His novels, reportage, autobiographical works, and political and cultural writings established him as an important commentator on the dilemmas of the twentieth century.