This book is a largely chronological account of Roman Catholic and Protestant missionary activity in Persia and the southern regions of the Russian Empire from the 1740s to the 1870s. Forced to abandon their missionary presence in Persia during the political chaos following the collapse of the Safavid dynasty, the Catholic monastic orders’ presence of prayer, hospitality and education was restored during the rule of the Qajar dynasty (1797–1925) through Jesuit missions in the northern Caucasus, Irkutsk and Tomsk from 1806 to 1820, and a Lazarist (Vincentian) mission to the (Nestorian) Church of the East in Urmia from 1838. During this same period several Protestant missions took advantage of incentives for foreigners to settle on the fringes of the expanding Russian empire in territories annexed from the mid-eighteenth century such as the Crimea (1783), and the north and south of the Caucasus mountains where Persia lost sovereignty at the turn of the nineteenth century. The most significant among these were the United (Moravian) Brethren agricultural colony among the Buddhist Kalmyks at Sarepta near Astrakhan, the Scottish Missionary Society's Karass mission among the Turkic tribes of the northern Caucasus, and the Basel Mission's work among Armenian Christians. Later sections of the book take us back into Persia proper to focus on the Nestorian mission of the congregationalist American Board of Commissioners for Foreign Missions at Urmia, and missionary work among Persian Jews by converted Jewish Christians sent by the London Society for Promoting Christianity among the Jews.

O'Flynn is concerned to dispel what he perceives as the myths created by contemporary revisionist critics who portray missionaries as interfering mischief-makers and colonialists promoting Western imperialism. He gives, therefore, a largely sympathetic account of the self-sacrificial and indomitable spirit of many of the missionaries who doggedly learned local languages, lived and travelled across hostile terrains, and immersed themselves in indigenous cultures. He assesses their contribution to the revival of religious, cultural and intellectual interaction between Europe and Persia, to the improvement of health care on Western models, and to the literary and educational development of the peoples whom they encountered through the creation of schools, literacy and the first translations and published texts in local vernacular languages.

He is not silent, however, about the conflicts, tensions and suspicions which arose, for example among the missionaries themselves at Karass or, in a pre-ecumenical era, between Protestants and Catholics working in the same place as in Urmia, or doing the same thing at the same time, as with the translation of the Gospels into Persian by both Don Leopoldi Sebastiani and Henry Martyn. He also sensitively draws attention to the dilemmas aroused by the presence of Western missions for the indigenous Christian communities: the emergence of Protestant congregations which divided the Church of the East and the Armenian Church and weakened the authority of their leaders, Catholic attempts to restore communion between the Nestorians and Rome, and the bewildering presence of disunited Western Churches with conflicting aims, ecclesiologies and missiologies.

It is in the area of both the long- and short-term impact of the missions on local Muslim, Jewish, Zoroastrian and Christian populations that the book is weak. Despite its 1,000-page length and its occasional, detailed forays into the mission archives, the book tells the story largely from the missionaries’ point of view, using their own diaries, reports, letters and communications with parent mission bodies. Much of this makes fascinating reading as far as it goes, but when we read of the shock among surrounding north Caucasian peoples at Henry Brunton's tracts with polemical criticism of Mohammed and the Koran, and the Patriarch of the East demanding that the American missionaries be expelled, we wish the author would tell us more about this reverse side of the story as viewed through local eyes.

Aware of this shortcoming, the author challenges Persian scholars to undertake such research from primary sources inaccessible to Western scholars. He could similarly challenge scholars to further research in Russian archives, which are more accessible yet also receive scant mention in his book. There is likewise little use of Russian secondary sources, so parts of the book show a marked ignorance of Russian missionary history in the same period. This is a major shortcoming in a book which has great significance for the wider history of Russian missions. For example, he rightly points to Mirza Muhammed Ali Alexander Kazim-Beg as one of the finest and most significant of the Scottish Mission's converts, not least because of his crucial influence on Nikolai Il'minskii whose influential missionary ideas and practices revolutionised Russian Orthodox missions in the late nineteenth century. O'Flynn is unaware, however, of how much of the inspiration for Il'minskii's promotion of local vernacular languages by indigenous translators can be traced directly to the work of the Russian Bible Society over which he enthuses in other sections of his book. His dismissal of Il'minskii's work, and Russian missionary work in general, as part of a politically motivated ‘divide and rule’ ideology merely aimed at russification is therefore not only illogical but lacks the generosity of spirit shown during much of the book towards Protestant missionaries who were carrying out translations into vernacular languages in much the same way as Il'minskii.

Nevertheless, O'Flynn's book is highly topical and informative at a time when war in the Middle East, the fate of its shrinking religious minorities, the plight of refugees and Russian claims to the Crimea are constantly being brought to our attention. Extensive footnotes and bibliographies, summaries of background information on everyone and everything, from the Great Awakenings in New England to the Jesuit missions in Latin America, from the Chechens to the Crimean Karaite Jews, make the book a veritable encyclopaedia of not only the eighteenth- and nineteenth-century missionary movement, but church history in its entirety. Amidst the plethora of books focusing on missionary history in Africa, India, Latin America and China, O'Flynn has boldly ventured into little-known and relatively inaccessible regions that remain insufficiently explored by historians and missiologists. In his painstaking and at times over-detailed and long-winded narrative, he opens up vistas on missionary lives, travels and motives as broad and breathtaking as the Caucasus mountains around which the story revolves. He also leaves many helpful markers on the trail, challenging scholars to engage in greater depth with this neglected region. The book will be a fascinating resource for historians of the Persian and Russian empires, church historians and missiologists, as well as scholars engaged with Muslim/Jewish/Christian and inter-Church ecumenical relations.