The Chabad-Lubavitch movement, one of the world's best-known Hasidic groups, is driven by the belief that we are on the verge of the messianic age. The man most recognized for the movement's success is the seventh and last Lubavitcher rebbe, Menachem Mendel Schneerson (1902-1994), believed by many of his followers to be the Messiah. While hope of redemption has sustained the Jewish people through exile and persecution, it has also upended Jewish society with its apocalyptic and anarchic tendencies. So it is not surprising that Schneerson's messianic fervor made him one of the most controversial rabbinic leaders of the twentieth century. How did he go from being an ordinary rabbi's son in the Russian Empire to achieving status as a mystical sage? How did he revitalize a centuries-old Hasidic movement, construct an outreach empire of unprecedented scope, and earn the admiration and condemnation of political, communal, and religious leaders in America and abroad? Ezra Glinter's deeply researched account is the first biography of Schneerson to combine a nonpartisan view of his life, work, and impact with an insider's understanding of the ideology that drove him and that continues to inspire the Chabad-Lubavitch movement today.