Hubert Wolf's fine book focuses on the German noblewoman Princess Katharina von Hohenzollern-Sigmaringen, and the secrets of the convent of Sant'Ambrogio della Massima in Rome that she unearthed during fifteen months of residence there. Twice-widowed and troubled by ill-health, she joined the convent in September 1858 after a lengthy trial period; its nuns belonged to the strictest order of the enclosed Third Order of Holy Saint Francis. But in July 1859 she wrote to her cousin of the abuse which she had suffered and in fear for her life. A confidant of Pope Pius ix, her cousin, Archbishop Gustav Adolf zu Hohenlohe-Schillingsfürst, titular archbishop of Edessa and the pope's almoner, eventually had her released.

The Church now faced a new scandal after decades of religious instability. Katharina made sensational claims regarding her time at the convent, of abuse, humiliation and attempts made on her life. In August 1859 she made allegations against the nuns of Sant'Ambrogio to the Roman Inquisition (the Sanctum Officium), and penned a formal denunciation out of ‘moral duty’. Her initial allegations centered around four main issues. The first was her own treatment in the convent including attempts to poison her. Likewise, the founding saint of the Franciscan community of Sant'Ambrogio, Mother Maria Agnese Firrao, was secretly venerated as a saint at the convent, despite her having been condemned as a false saint whose supposed miracles and divine gifts were ‘nothing but deceptions, boasts, [and] falsifications’ (p. 95) by the Roman Inquisition and her cult forbidden. Next, the beautiful young mistress of the novices, cellarer and madre vicaria with ‘almost irresistible charm’, Maria Luisa of St Francis Zavier, had made claims of ‘feigned holiness’, that she possessed the supernatural powers and ‘heavenly gifts’ of a living saint, including a scent of roses and the ability to heal the sick with a ring of ‘mysterious power’. Lastly, Katharina denounced the same woman as having a ‘highly suspect relationship’ with the ‘possessed man’ Pietro, known as ‘The Americano’, whom she allegedly was attempting to free from demonic possession (pp. 24–5, 27–31).

In addition, the results of the preliminary investigation found that the convent's novices had shared improper intimacies and kisses with the novice mistress, including lesbian initiation rites and love-making. Maria Luisa was also accused of forcing novices to confess to her. The novices were charged with not having followed significant convent rules. The nuns were charged with concealing a range of objects linked to the forbidden cult of Agnese Firrao. Lastly, the convent's confessors were alleged to have at the very least tolerated all these offences and done nothing about them. After a preliminary investigation, and authorised by Pope Pius xi, the trial itself began in December 1859 and concluded in February 1862 with judgements meted out against the novice mistress (in Wolf's words: ‘the churchmen who had previously hung on Maria Luisa's lips and breasts, venerated her as a living saint, now dropped her like a hot potato’, p. 347) and other major protagonists and the former convent itself was to be destroyed and the body of its mother founder anonymously reburied.

As the title suggests, there is a strong element of the dramatic about the organisation and marketing of this volume which is meant to appeal to a wider audience; at times, Wolf's storytelling is reminiscent of crime fiction with its focus on the lurid and scandalous details which emerge. Indeed, it begins with a list of the dramatis personae. The prologue tells of Katharina's dramatic rescue from the convent with the help of her well-connected cousin. Chapters i–ii chiefly comprise a narrative of events relating to Katharina and the initial proceedings against the nuns of the convent after her denunciation, including evidence about illicit lesbian relationships amongst the nuns. Chapter iii is concerned with the ‘false saint’ and mother founder Firrao, and explores the historical background to her illicit cult and relics as well as concepts of false and true holiness. Chapter iv examines Maria Luisa of St Francis Xavier and her ‘feigned holiness’, from the very worldly origins of her miraculous ring and sweet scent to forged letters from the BVM, her initiation of ‘lesbian intimacies’ and her affair with Father Pietro. Chapter v deals with her intent to murder Katharina, from letters foretelling her murder to attempts on her life through poisoning, her search for various poisons, her murder of at least three other nuns, and other crimes like embezzlement. Chapter vi focuses on the interrogation of Maria Luisa, examining, amongst other topics her history, the novices and the issue of sexual abuse, the Jesuit confessor and his affairs, and her confessions. In chapter vii Wolf concentrates on the interrogations and confessions of the abbess and the father confessor of the convent, and in chapter viii on the identity and interrogation of Giuseppe Peters (Padre Peters, aka the philosopher and theologian Joseph Kleutgen). Chapter ix is concerned with the final verdict in the matter and the fate of the major protagonists. The epilogue examines how the ‘secret of Sant'Ambrogio’ has been ‘judged by history’, and publicity and historiography concerning it and the Curia's strategy to contain ‘what had sounded like an outrageous fantasy but turned out to be a true story of a convent in scandal’ (p.371).

Wolf's study offers a compelling combination of biography, testimony, narrative and discussion of the wider historical context to convincingly reconstruct the events of 1858–62 and beyond. Wolf synthesises the narrative of the scandal and subsequent investigation and trial well with broader contextual discussions, for example of the legal process, individuals, nineteenth-century Catholicism, mysticism and the ‘Marian Century’, convent life, ecclesiastical politics, sainthood and holiness, attitudes towards sexuality, confession and more. What emerges is a narrative which as a result dwells primarily on the religious and political aspects of the case more so than the psychological or social; perhaps more discussion of these aspects might have been beneficial in adding further nuance to our understandings of the main protagonists and their worlds.

The book is meticulously researched. Wolf's main sources for the trial are numerous unlabeled files relating to the Roman Inquisition's trial found in the very secret Archive of the Congregation for the Doctrine of the Faith (ACDF) in the Vatican archive; this was only opened to the public in 1998. Likewise, in 1870, Katharina's collaborator, Christiane Gmeiner, penned her detailed report, entitled Erlebnisse (Experiences), an autobiographical account of the princess. Overall, this volume is very readable and engagingly written. Ruth Martin's translation from the original German flows well and is never awkward. Wolf is to be commended for approaching the shortcomings of the Church directly and without hesitation. While it would have been easy to speculate or sensationalise, he refrains from this and approaches the material with a strong evidence-based approach which is quite successful. Overall, then, this book offers a persuasive, knowledgeable and memorable account of the realities of this nineteenth-century convent scandal.