Set in London before the First World War, it is narrated by Margaret Trant, who lives with her ailing, irascible mother in a boarding house in St John’s Wood. Since the death of her father, Margaret and her mother have fallen on hard times, with only Margaret’s meagre salary from Plimpson & Co to keep them afloat. When circumstances force Margaret to leave her employer, she finds herself mysteriously guided into a new position as a secretary in a dingy backstreet shop. But all is not as it seems, and she is in fact working for a highly secret branch of the intelligence service, whose mission is to track down and neutralize the ruthless band of anarchists known as The Scorpions. Margaret’s love of mystery fiction scarcely prepares her for the reality of true criminality, and her journey of self-discovery forms the heart of this remarkable novel, as she discovers in herself resourcefulness, courage, independence and the first stirrings of love.