About the book: 2020 / In a chess game by correspondence, an old friend of lawyer Ardashev, Professor Posse, indicating the next move, reports that he managed to create a theory for guessing “lucky” numbers lotteries. Then, instead of letters, telegrams come from the professor with strange chess moves leading to a quick loss. The lawyer suspects something is wrong and leaves for Tuapse. Suddenly, a series of brutal murders occurs in the city. And one of them, as it turned out, was committed by Klim Ardashev…