This book is essentially based on previously unknown archival sources and newspaper articles. Chuprov (1874-1926) is shown as a scientist with a broad field of interests (statistics with various applications including natural sciences, mathematical statistics, economics, burning social issues). His particular findings in mathematial statistics are described and also his efforts, partly successful, of uniting the Continental direction of statistics and the Biometric school into a single mathematical statistics. For the first time, Chuprovs life in emigration (mostly in Germany) is described in detail. He was recognized by the scientific community, elected Honourable Fellow of the Royal Statistical Society, and worshiped by Russian statisticans, but up to ca. 1958 Soviet officialdom labelled him an ideological enemy.