Neurologist Oliver Sacks presents twenty-four case histories of patients with unusual neurological and neuropsychiatric conditions, grouped into sections on losses, excesses, "transports," and the world of the cognitively simple. The title case concerns a musician who can no longer recognise faces or ordinary objects, to the point of mistaking his wife's head for his hat. Combining clinical insight with deep compassion, Sacks treats each patient as a complex individual rather than merely a set of symptoms.