Russian brothers Arkady and Boris Strugatsky began to collaborate in the early 1950s after Arkady had studied English and Japanese and worked as a translator and editor, and Boris was a computer mathematician at Pulkova astronomical observatory. The Encyclopedia of Science Fiction describes them as "the best Soviet SF writers," and their novels are as powerful and visionary as ever. (blurb) Anton is an undercover operative from future Earth, who travels to an alien world whose culture has not progressed beyond the Middle Ages. Although in possession of far more advanced knowledge than the society around him, he is forbidden to interfere with their natural progress of development. His place is to observe rather than interfere—but in this 1965 novel, can he remain aloof in the face of so much cruelty and injustice?