In 1930, George Riddoch, Charles Symonds, Russell Brain, Hugh Cairns, Macdonald Critchley, and Derek Denny-Brown formed the Hexagon Club with the aim of discussing over dinner developments in medical and surgical neurology. Over the next ten years, they met on thirty-two occasions, sometimes with guests, and discussed forty-two topics of past or emerging clinical and research interest. Honed in this way, the presentations led to a large number of publications, many of lasting importance. This was a time of transition in medicine and society. The members’ lives illustrate the experience of medical service in the First World War carried forward to responsibility for developing neurological services during the Second World War; training in neurology and neurosurgery with independence from general medicine and surgery; developing the model of specialist departments distributed in regional centres adopted by the National Health Service; and the interplay of neurology and culture. Based on the only surviving copy of the Hexagon Club minutes and other previously unknown archival material, the book is written by a specialist able to summarise complex topics in neurology. It will attract general readers with an interest in medical history, neurologists and neurosurgeons interested in the evolution of their professional work, and historians of the medical profession in society during the middle decades of the twentieth century.