The manuscript no 35 of the Manuscript Collection of the John Rylands Library in Manchester contains a Turkish text in Latin script from the Diyarbakır region dated 1768. The text represents verses from the Gospels and Old Testament, religious teachings and quotations. The Turkish-language transcription takes up 32 folios. The author, Father Gery Desiré, remains a mystery. The Archives of the Capucin Friars in Paris do not seem to hold any mention of missionary activities in eastern Anatolia during the 18th century. A comment on folio 11 v of the manuscript suggests that the Turkish-language texts were used by Father Desiré in “converting” Armenians who spoke Turkish to Catholicism. The present volume consists of the French version by Father Desiré, the Turkish version in Latin script by Father Desiré, the Turkish text in modern transcription, an English translation of the Turkish text, and a study of the language of this extraordinary artefact.