The origins of the Round Table, according to Layamon’s Brut, lie in a festive food fight. When the storm of bread rolls and spilt wine gives way to smashed jaws and slit throats, King Arthur acts decisively. The instigator’s corpse is left to rot in a bog, his male relatives are put to death and his female kin are mutilated so that his line will end forever. A Cornish carpenter then suggests a solution to the problem of precedence that started it all: a round table. Merry Christmas from Camelot.

Amy Jeffs’s Arthur: A New Life charts these dark and bloody beginnings of the legend. Geoffrey of Monmouth may have given the shadowy Celtic hero his first coherent biography in the 12th century, but we are far more familiar with Thomas Malory’s 15th-century blend of pseudo-history and continental romance. In Le Morte Darthur, the Round Table represents the civilising ideals of chivalry: a bittersweet vision reimagined in the jewel-toned reveries of the Pre-Raphaelites, the pastel whimsy of Walt Disney and the mud-spattered iconoclasm of Monty Python. The earlier sources, however, are stranger.

Jeffs’s book reminds us that this is an uncanny realm, far from the courtly fantasies of hennins and heraldry. Merlin, a wildman prophet, is fathered by an incubus; the towering, furious Guinevere descends from a giant named Ogfran. Arthur is fairy-fostered in one tale and recuperating inside Mount Etna in