The Witch's Brat is set in 12th century England. Lovel, a villein, or serf, in the Downs country of Britain (familiar territory for Sutcliff) is cast out of his village following the death of his grandmother; a "witch's brat," in the eyes of the simple, fearful villagers, as much because of his hunched shoulder and twisted leg as the knowledge of herbs and healing he learned from the old woman.
He finds sanctuary at the New Minster outside Winchester, a monastery and hospital. There, Lovel connects with Rahere, the king's jongleur (a cross between a minstrel and a fool), taking shelter from a storm one night. Rahere takes a liking to the boy with the "bony face that was quick and eager and wanted to be friendly," and asks Lovel "If I were to come back and whistle you out of here one day, would you come?"
Five years pass, and in that time, Lovel comes to be an herbalist and healer, working with the monks and considering taking vows so that he can truly practice his craft. Rahere comes for him, no longer a jongleur and with a vision to start a hospital in London. Lovel joins him and, in finding his place and his peace, realizes the vision that his grandmother foresaw for him long ago: that he "will be one of the menders of this world; not the makers nor yet the breakers; just one of the menders.