London, 1952. Seven years after the chaotic aftermath of World War II, London has is coming alive again, with jazz clubs and flickering cinema awnings lighting up the night sky. But for widowed Helen 'Dexie' Dexter, she's still a woman in a man's world. She longs to prove herself as an officer in the London Metropolitan Police, yet she's stuck intervening in domestics and making tea for her male colleagues. Then Harri Schroder arrives, seconded from Hamburg to the Met. Haunted by the loss of his wife and child, Harri is unlike any man Dexie has ever known. Compassionate and sharp-witted, he sees her not as a threat, but as an intelligent, canny officer full of potential. And when Harri is tasked with hunting down a Nazi war criminal-turned-respected-businessman, with connections to the upper echelons of British society, it's Dexie he turns to for help.