Shepherd has reimagined the clinical case history in this book, but it is not a book on the history of delusions. Indeed, her topic is delusions and her approach is the case history format, focusing on individual cases. But what she does is not a formal history of the nature and narrative of delusions. She describes unusual and false beliefs, and she sets these beliefs in the social context of the individual and supplements the account with the circumstances of the clinician who described the case, revealing what we know about him and then drawing out what the social and political contributions were. This is an advance on the traditional clinical method.

This approach is most successful when she discusses Capgras syndrome, describing Capgras and Reboul-Lachaux's original case, Madame M. We learn as much about Madame M as we do about Joseph Capgras, who trained in Toulouse and gravitated to psychiatry under the influence of his uncle, an asylum doctor in the Paris area. Shepherd recounts the initial presentation at a meeting of the Société Clinique de Médicine Mentale, and in true journalistic style, she informs us of Capgras’ dramatic flourishes at the meeting, of de Clérambault's interventions at the meeting, and of the importance of the social context of Paris in the years after the First World War to the concerns that Madame M expressed.

Shepherd discusses the case of James Tilly Matthews, who was admitted to the Bethlem on 28 January 1797 and was treated by John Haslam and described in Haslam's Illustrations of Madness. Although the content of Matthews's abnormal beliefs is interesting, unlike Capgras’ description of Madame M, the case has not gone on to influence psychiatric thought or practice. Furthermore, Shepherd discusses the melancholic delusions of Robert Burton, author of The Anatomy of Melancholy, but there is little evidence that Burton had any delusions, except if an interest in, or even a preoccupation with, astrology was to be regarded a delusion. Nor is there much evidence that Francis Spira, one of her other cases, held any recognisable delusion aside from being severely depressed and dying from inanition.

Shepherd's account of King Charles VI of France's delusion of being made of glass is convincing and fascinating. She gives a detailed account of the development of the King's malady and sets the delusional belief firmly in the context of the rise to prominence of glass-making and the enthralling symbolism of glass during Charles's reign. Shepherd allies the content of Charles's delusions with the equally important fact that the content of delusions can and does incorporate new technologies as they arise. This aspect of the content of delusions – the pathoplasticity – is further explored in her description of Napoleon and the rise and rise of Napoleonic delusions of grandeur.

There is much to commend Shepherd's book. Even though it deals with the surprising and the truly bizarre content of delusions, it treats the individuals she describes with respect. There are minor issues that you would expect from a psychopathologist: she conflates autoscopy (the double) with Capgras syndrome, but that error is often made; she asserts some cases as having delusions where there is little evidence to support her charge. Nonetheless there is a freshness and a genuine enrichment of our understanding of the social and cultural context of delusion formation in her book.