In an alternate London where the British Empire dominates the world through control of magic, and commoners are governed by the ruling class of magicians, five-year-old Nathaniel begins an apprenticeship to magician Arthur Underwood, Minister of Internal Affairs after his unknown family forfeit him as part of a government program which pays parents to give up their children for this purpose. Despite Underwood's disinterest, his wife Martha welcomes the child. Over the following years, Nathaniel receives a classical education and insight into magicians’ power: magic is performed by a hierarchy of otherworldly spirits that magicians, with adequate knowledge and willpower, can summon and bind into service.