N ews of the arrest of a Russian spy operating inside the British embassy in Berlin sent shockwaves around the world in summer 2021. The mysterious David S – as he was then known – had been secretly leaking intelligence to his Russian paymasters and an undercover mole hunt had turned up the spy within. Memories were evoked of the notorious Cambridge Spy Ring, when the Queen’s art historian Anthony Blunt, together with Guy Burgess, Kim Philby, and Donald Maclean, infiltrated the upper echelons of British society to betray their country. Now, in Berlin - a city that was a...