This is the first of four Rex Carver mysteries by Silver Dagger winner Victor Canning, from 1965. The fast-paced thriller opens with the laconic London private eye accepting a seemingly simple job of tracing a German au pair gone missing. But Carver soon finds that the beautiful Katarina's whereabouts are of interest to a great many people, including intelligence agents from London, Bonn, Washington, and Moscow. Working in the dark, but determined to keep Katarina safe, Carver will need every bit of his ingenuity and instinct as he follows her across Europe and entangles himself more and more deeply in a dangerous game of international espionage and double-dealing.