Hugo Marcus (1880-1966) was a man of many names and many identities. In German, Jew, Muslim, Gay, Marc David Baer uses Marcus's life and work to shed new light on a striking range of subjects, including German Jewish history and anti-Semitism, Islam in Europe, Muslim-Jewish relations, and the history of the gay rights struggle. Perhaps most significant among the important contributions of Baer's brilliant biography of the queer, German-Jewish convert to Islam, Hugo Marcus, is the new perspective he offers on the history of Jewish-Muslim relations. Not only Marcus's engagement with Islam but also that of other Jewish converts to Islam-as well as that of Jewish 'Orientalists'-allow Baer to demonstrate the mutual 'Semitic' affinity of Jews and Muslims.