Over the years, Thomas O'Loughlin has used his theological expertise to throw considerable new light on the writings of Adomnán, the ninth and, after Columba, the best-known of the abbots of Iona. In previous studies O'Loughlin has concentrated mainly on issues arising from Adomnán's biography of Columba. Here, he turns his attention to the De locis sanctis, arguably the most famous work of the abbot of Iona, at least in the Middle Ages when numerous copies were made of it. In a study as insightful as it is thought-provoking and comprehensive, O'Loughlin places Adomnán where, on the evidence of this study, he clearly belongs, at the centre of a text designed to resolve problems raised by Scripture. Often regarded as incidental to a story told to him by a shipwrecked pilgrim, Adomnán is here shown to have deliberately taken a topographical approach to certain scriptural problems, thus generating the need for an actual eye-witness to the places he was describing. For O'Loughlin, the question as to whether Adomnán's informant, Arculfus, whom previous studies have tended to place at the centre of the De locis ever existed is beside the point; Adomnán needed him, or his like, to help solve the scriptural aenigmata that he set out to address. Structuring his text according to an agenda set by the writings of such other exegetes as Augustine, Jerome, Cassiodorus and Eucherius – the latter's De situ Hierusolymae being perhaps his main model – Adomnán produced a textbook on selected thorny issues that not only captured the imagination of contemporaries and later readers, including Bede, but also threw considerable light on the intellectual culture of his time on Iona, where, as is shown by closely argued case studies of such issues as Adam's burial at Hebra or the various gospel accounts of Holy Week, excellence lay in recognising the flaws in received wisdom. Minutely pursued case studies of such miracles as the marvel of the rain that flushed out Jerusalem after market, the wind that blew on Ascension Thursday and the wait for Christ's Resurrection, are expertly turned to account here in order to demonstrate Adomnán's well thought-out position and his ‘definite contribution’ to western theology, an aspect of the author that has rarely received consideration up to now. Indeed, O'Loughlin persuasively argues the case for viewing Adomnán as a sophisticated theologian, very much at home within the style of Latin theology of his day. In a final chapter, the author usefully reviews the impact of Adomnán's text on its medieval readers, including Bede, who, pace previous opinion, is portrayed here in the role of discipulus to the Irish magister, when composing his own De locis sanctis. Nine valuable appendices conclude this study of Adomnán's De locis, whose central thesis, as summed up by the author, is that it is a work of scriptural scholarship. Not all scriptural scholars may agree but the opinions expressed in this work, however novel they may appear against the background of the side-lined Adomnán of previous studies of the text, are ably defended here in an extremely closely-argued work. This book cannot be said to have been presented by its publishers in an easily readable fashion; nor is its author's approach to his subject entirely faultless. There is, for instance, little or no indexing, and there is scant evidence of a competent acquaintance with the vernacular literature on Adomnán, with no mention of his vernacular Life, and with notes on the saint in the commentary to the ‘Martyrology of Óengus’ placed here in the ninth rather than in the twelfth century. But apart from flaws such as these, which are minor in the overall context, Thomas O'Loughlin's study of Adomnán's De locis must rank as a major contribution to the history of insular scriptural scholarship in the early Middle Ages.