Demonic possession has been a source of ongoing fascination for historians of successive generations. The search for its causes, and indeed for explanations, has produced a varied historiography in which agreement or consensus is not always available. The great virtue of Sari Katajala-Peltomaa's contribution to this field – focused on later medieval Europe, and in particular on a set of canonisation proceedings located especially in North Italy and Sweden – is that it allows space for these competing interpretations, and builds an intellectual framework which can contain and contextualise this multiplicity.

With a useful introduction and conclusion framing them, the book is split into six concise chapters, each of which inspects the volume's sources from a different perspective: first the explanations given during canonisation proceedings for demonic possession, then an examination of the type of ‘vulnerable persons’ often afflicted; followed by investigations of the ‘community response’ to demonic presence, the construction of the sacred which took place simultaneously and alongside the investigation of the diabolic, and also of the political and finally the sexual battles which can be perceived to be fought in the stories Katajala-Peltomaa uncovers.

This approach can lead to a certain gentle dislocation: at no point does the volume simply narrate the cases of demonic possession that the author has found in her sources, proceeding from these basics to further and deeper discussion. Instead, the series of lenses is applied in succession often to the same cases, leaving the reader each time rather dependent upon Katajala-Peltomaa's interpretations. Some might have preferred to have a clearer sense of the sources prior to embarking on thematic readings.

The book's approach nevertheless bears real fruit. This is especially thanks to the author's adoption – and innovative use – of ‘religion as a lived experience’. Katajala-Peltomaa understands this phrase as a way to approach faith ‘as a social process, a way to live, interact and participate in one's community’ (p. 2). In examining religious life from this cultural perspective, she seeks a means of uncovering individuals’ agency, and of better understanding the exchange between ‘authorised’ theology and ‘popular’ belief which created the religion that people really practised. Of particular interest is the manner in which Katajala-Peltomaa employs this concept: ‘lived religion is not only a theoretical framework for … analysis but also a methodological tool: a way to read the sources’ (p. 19). In other words, the volume approaches these sources in a targeted way, unpicking them specifically for evidence of how everyday religion was arrived at, negotiated and practised.

This is a useful methodological approach for a book which contends that ‘demonic possession was … a process requiring collective negotiation’ (p. 28). Throughout the volume, Katajala-Peltomaa demonstrates that, even in the context of canonisation proceedings led by clerics for ecclesiastical purpose, lay witnesses were an important part of how boundaries were located and defined. This certainly seems a special feature of these sources: unlike other accounts of demonic possession, ‘finding someone to blame for the misfortune was not the main aim’ – since of course the primary goal was to identify and verify the miracles which might justify a candidate's sainthood. Perhaps consequently, Katajala-Peltomaa uncovers ‘the accidental nature of possession’ (p. 45) – an absence of any explicit link between an individual's sin or sinfulness and their likelihood of playing host to a demon. She is aware that ‘hagiographic material is not necessary the most reliable source’ (p. 84), and usefully reflects on what can and cannot be concluded from this quite narrow corpus; but she is nevertheless bold in arriving at new understandings of demonic possession that differ especially from the early modern historiography (she takes particular issue, for example, with Brian Levack's argument that demoniacs were merely acting out a sort of cultural performance, simply playing out a role given to them). The book's openness to this sort of variation – in comparing the Italian and Swedish cases, she also finds distinct regional variation, for example in the way the cases in these diverse locations considered and imagined political authority and allegiance – becomes its great strength, and indeed its primary contribution to the field.

In this volume, we see that ‘gender was seen as a multifaceted, not binary, system’ (p. 46); that ‘demoniacs came from all walks of life, and manifested variable symptoms, [and so] the responses to their afflictions also varied’ (p. 93); and that ‘views about spirit possession were not always unanimous’ (p. 110). This resistance to totalising interpretation energises the volume and lends an outsize productivity to its approach to what remains a relatively small subset of cases. Katajala-Peltomaa demonstrates that contemporaries were well aware of demonism's variation, and engaged in complex dialogue to construct consensus approaches that saw clerics and laity achieve a collective view – even identity – that transcended dispute. For example, she argues that ‘demonic presence played a part in … enhancing a community's coherence’ by offering the historian an opportunity to express and explore political allegiances, matching the particular saint called upon to resolve a given case of possession with the local political elite associated with them. Read in this way, ‘cases of demonic possession were a way to draw the boundaries of a cultic community’ (p. 149).

It is always easy to accuse these kinds of cultural history of back-filling gaps in the material with too much colour. It is certainly true that some of Katajala-Peltomaa's examples are more convincing than others – does her examination of the disruptive role of dancing really bear the interpretative weight the volume asks of it when the author admits that ‘dancers did not verbally summon demons, but, according to clerical authorities, bodily gestures communicated an association with them’ (p. 155)? Readers may disagree. But each of this book's relatively short chapters is split into further, still shorter, subsections – and so much variation of interest is covered here that the book comes amply to demonstrate its case: that demonic possession was a fissiparous phenomenon that can reward close and creative readings with new understandings of how late medieval religion worked in practice and in dialogue.