Both an American agent posing as a lawyer with the United States Embassy in London, and a Scotland Yard detective posing as a music critic, try to get close to a famous singer whom they suspect of espionage. George Brent as Tim Hanley Ilona Massey as Carla Nillson Basil Rathbone as Reggie Oliver Gene Lockhart as Sidney Grenner George Zucco as Webster Francis Pierlot as Dr. Rowan Martin Kosleck as Bruner Charles D. Brown as Tetlow Marjorie Gateson as Bertha Grenner Leyland Hodgson as Sergeant Moulton Clayton Moore as Sewell