The title of this book, with its promise of the ingredients of a bestselling novel, might induce some scepticism in potential readers. However, the title is in fact an accurate description of its contents, and although some of the incidents that Callan deals with are sensational, this is not a sensationalist work and it is written in a clear, sober style with extensive academic apparatus. It is a well-made volume illustrated by several of the author's own photographs (not all of which are necessary – it is difficult to justify a picture of Trinity College Dublin simply because it was later built near the site of a 1328 execution). This volume is the first book-length account of medieval Irish heresy trials, phenomena that both emerged and disappeared in the fourteenth century. It discusses Irish heresy in a European context stressing the cultural and political aspects of heterodoxy. The most notable political element is an interpretive framework that locates heresy proceedings in the troubled relationships between the Irish, the English and the Anglo-Irish, and the place of the Church in this system: heresy proceedings could be used as tools of colonisation. Some readers might be unhappy with the idea that people were motivated by ‘nationalism’ (p. 129), and the terminology associated with the Anglo-Irish and colonisation is often disputed, but for my part I found Callan's stance perfectly clear.

Callan points out that the early reputation of Ireland as a ‘land of saints and scholars’ had become quite tarnished in Europe by the later medieval period. Some of this arose from complex confections of distinctive features of the Irish Church and expediency (such as that required by Henry ii and Laudabiliter). The book's focus is on eight instances of alleged heresy in the fourteenth century. The first of these were the trials of the Templars. These occupy a foundational position in the history of Irish heresy cases. The appointment of Thomas de Chaddesworth of St Patrick's Cathedral, Dublin, as an inquisitor of the Templars inspired him to bring heresy charges against Philip de Braybrook (of the rival Holy Trinity, now Christ Church Cathedral, Dublin). Callan points out plenty of indications, here and elsewhere in her book, that heresy proceedings were deployed on the basis of evidence manufactured for personal or factional gain. The Templar trials in France inspired Richard de Ledrede, who was resident in Avignon before he was appointed to the bishopric of Ossory, where, in addition to engaging in the well-known heresy proceedings of Alice Kyteler and her associates, he was involved in three further heresy cases: charging Robert de Cauton, a valued servitor of Maurice fitzThomas, lord of Desmond, and Alexander de Bicknor, the archbishop of Dublin (who had extended his protection to Cauton). Bicknor retaliated in kind and Ledrede himself faced a heresy accusation.

At the core of the book are chapters on Kyteler and her nemesis Ledrede. Kyteler's story is well-known and it is easily accessible in The sorcery trial of Alice Kyteler, a collection of documents related to the proceedings that were translated into English by L. S. Davidson and J. O. Ward (1993). The Kyteler case is a particular challenge for the book then: it cannot be omitted, but it is not obvious how much of substance remains to be said about it. What Callan adds is her location of Kyteler in the general contexts for Irish heresy, including the political context at the heart of the book. Callan points out that she also stresses gender, but it is less evident that this has been ignored previously. She provides a sustained and detailed reading of the episode which, in a positive sense, extracts every detail from the comparatively extensive primary and secondary literature. In doing this, a chronological overview of the case is provided, but this inevitably overlaps with the background and analysis sections and I found the repetition a bit odd. This is a minor quibble though, and Callan's book is clearly a compulsory point of reference for future scholarship.

The book's fifth chapter is titled ‘The heresy of being Irish’ and it deals with two cases. Adduc Dubh O'Toole, a member of a Wicklow family that often raided Dublin, was supposed to have denied the Incarnation, the Trinity, and both biblical and papal authority, in addition to stating that the Virgin Mary was a whore (Callan thinks the accusations were specious). He was burnt at the stake in 1328. In 1353 two MacConmaras were burnt at Bunratty Castle after a trial by the bishop of Waterford that unearthed evidence that they too had unorthodox beliefs about Mary: they were the last people executed for heresy in Ireland. Callan's argument is that these three men ‘were most likely killed for their ethnicity, not their religious beliefs’ (p. 234) and to demonstrate this she points out how the prosecuting authorities were aligned with Ireland's colonisers.

Drawing conclusions about intentions, as Callan does, will always be difficult in an area that must rely on a limited range of contemporary sources: it is impossible to be at all sure, for example, that Ledrede had ‘a predisposition to interpret disrespect for him as heresy’ (p. 169). In some matters, historians can appeal to general trends and analogies; but, as the book under review shows, accusations of heresy in medieval Ireland were rare, and an idiosyncratic individual such as Ledrede influenced several of them. A solid argument is provided by Callan for the importance of an awareness of colonial motivations in heresy proceedings and it is not to be expected that she should devote too much time to those scholars who focus on theological or ecclesiological aspects of them (footnotes provide the trails of other approaches so she is perfectly fair). I find it easy to imagine that figures such as Ledrede, whom Callan shows as motivated by spite, was simultaneously appalled at the discovery of heterodoxy, real or imagined. None of this detracts from the fact that this book is a thorough and often distinctive treatment of the remarkable history of medieval Irish heresy.