No doubt I will not be the last to remark that this is the most fascinating book Patrick McGrath did not write. It has all the ingredients of one of McGrath’s icily stylish novels: madness, violence, arcane obsessions, weird learning, ghastly comedy, all set out in an atmosphere of po-faced, high neo-Gothic. The geographical span is wide, from Dickensian London to Florida’s Pensacola Bay, from the beaches at Trincomalee to the Civil War battlefields of the United States. The main characters are a pair of Victorian gentlemen, learned, serious, highly respectable, remarkable only in that one of them is a lexicographer of genius, the other a madman and a murderer.

The story was already known. The journalist and author Simon Winchester first came across it, he tells us, in Jonathan Green’s 1996 study, Chasing the Sun: Dictionary Makers and the Dictionaries They Made, which sent him on to Caught in the Web of Words, a biography of James Murray, the first editor – in effect, the maker – of the twelve-volume Oxford English Dictionary, written by Murray’s granddaughter, Elizabeth Murray.

The OED is one of the greatest legacies of the Victorian age of endeavour and optimism. It was initiated as a conscious effort to define and fix the English language, that vital tool of empire-building. The idea was first floated in 1857 in an address to the London Philological Society by the Dean of Westminster, Richard Chevenix Trench. A dictionary, he declared, ‘is an historical monument, the history of a nation contemplated from one point of view’, and he went on to recommend a comprehensive lexicon of the language that, as Simon Winchester has it, ‘would demonstrate not merely meaning, but the history of meaning, the life story of each word …. The task would be gigantic, monumental and – according to the conventional thinking of the times-impossible’. Trench, however, had a plan:

The undertaking of the scheme, he said, was beyond the ability of any one man. To peruse all of English literature – and to comb the London and New York newspapers, and the most literate of the magazines and journals – must be instead ‘the combined action of many’. It would be necessary to recruit a team – moreover, a huge team, one probably comprising hundreds and hundreds of unpaid amateurs, all of them working as volunteers.

The man chosen to head this army of bookworms was James Augustus Henry Murray. He was born in 1837, the son of a Scots tailor, and was a man of awesome energy and learning, one of those rare yet quintessential nineteenth-century savants. He left school at fourteen owing to poverty, but went on to educate himself, becoming a kind of walking encyclopaedia, with a particular linguistic gift – he spoke, or at least had a working knowledge of, practically every language, ancient or modern, known to man.

The Philological Society first appointed Herbert Coleridge, the poet’s grandson, to edit the New English Dictionary on Historical Principles, but he died young, and not even halfway through the letter A. Next to take over was Frederick Furnivall, Secretary of the Society, a colourful character who had no intention of allowing the job to interfere with his devotion to teaching young waitresses from the ABC teashop in New Oxford Street to become skilful rowers of a racing boat of his own design. Furnivall, though he hired a team of assistants to help him collate and edit the submissions from the army of volunteer readers, gradually lost interest, to the point that the Athenaeum reported in 1863 that it was unlikely the Dictionary would be completed.

However, the magazine had not reckoned with James Murray, who in 1878 was appointed by the Delegates of the Oxford University Press to revive the project. He immediately set to, building in the grounds of Mill Hill School, where he was a teacher, a corrugated hut, to which he gave the sonorous title The Scriptorium. He also produced a four-page appeal for a new corps of volunteer readers, a copy of which found its way to one of two large cells on the top floor of Block 2 of the Broadmoor Asylum for the criminally insane in Crowthorne, Berkshire, where it was ‘read voraciously [Mr Winchester is never one to let a serviceable cliché pass unused] by William Minor, a man for whom books, with which one of his two cells were [sic] lined from the floor to ceiling, had become a second life’.

William Chester Minor was born in Ceylon in 1834, the son of an American missionary. Although he left the island while still a boy, he was to attribute his lifelong sexual cravings to his childhood glimpses of naked Sinhalese girls gambolling in the surf at Trincomalee. Back in America, he graduated as a surgeon from Yale Medical School in 1863, at the age of twenty-nine. The Civil War was by then half over. Minor signed up for the army four days before the Battle of Gettysburg, one of the fiercest and bloodiest battles of the war. He witnessed his own personal holocaust, however, at the Battle of the Wilderness, in Virginia, in May 1864.

The fighting Minor saw in the Wilderness was terrible, but worse was to come when he was ordered to brand the letter D with a red-hot iron into the cheek of a young Irish deserter. The experience, it was said, drove him mad. Most likely, however, he had been a latent schizophrenic. His reason quickly deteriorated, he suffered from paranoia, and eventually the army pensioned him off. He moved to London and took rooms in Lambeth, where, in the small hours on a winter night in 1871, he chased and shot dead a young working man, George Merritt, whom Minor in his madness had taken for one of his imaginary tormentors. He was captured, tried and sent to Broadmoor for life.

Minor turned out to be one of Murray’s most productive readers, supplying him and his team with tens of thousands of slips of paper, each containing an illustrative quotation of this or that word, culled from the book on his shelves. All communication was by post, and it was assumed that he was a private scholar of a shy disposition. It was not until 1897 that Murray at last made an excursion to Broadmoor and discovered, to his astonishment, the true circumstances of his most valued reader. The two became friends, despite Minor’s continuing dementia, and Murray gave a generous mention, in his introduction to the OED, to ‘Dr W C Minor’.

It is a wonderful story, and Simon Winchester has done a workmanlike job in the telling of it. His efforts to achieve a racy style are not always successful, especially when he goes for a Dickensian effect (the opening chapter, in which he describes the murder of George Merritt, is toe-curling in its banality), although his recounting of, for instance, the history of English dictionary-making is a model of narrative control and drive. The book will likely be a great success, in the line of Longitude and Fermat’s Last Theorem. The blurb announces that Luc Besson has bought a film option for $2 million. One can easily imagine the film, with Gary Oldman as Murray, Tim Roth as the murderous Dr Minor and Uma Thurman as the Dictionary.