The Spy in Black was also an erotically charged espionage thriller for its day, with the fierce love-deception relationship of its two leads, both spies. "One of a number of films made on the threshold of World War II which seemed to say that if war came, there was no reason why it couldn't be conducted along the gentlemanly lines of certain aspects of the previous war. Of course, this largely depended on one's opponent turning out to be like Conrad Veidt! The Spy in Black is one of the best of the earlier Powell thrillers, casting visual echoes from Nosferatu, using a fine (early) score by Miklos Rosza, and mixing studio work with well chosen locations in the manner of so many later Powell films. It's literate, exciting, extremely well crafted-and in the early days of the war was rather comforting as well...The soon-to-be common notion that Britain was overrun by rather nice people, including little old ladies, who were actually German spies got the upcoming spy cycle off to a good start. (Here) was a Hitchcockian blending of humor and thrills..." (William K. Everson)