“Lang's mystery thriller Spies featured a master spy who led several lives: besides the spy, he was also the president of a bank and a music hall clown. This film refrained from conferring moral superiority upon the representatives of the law. Espionage and counterespionage were on the same level - two gangs fighting each other in a chaotic world.” --Siegfried Kracauer.
“The structure of the film is flawless, and Lang builds and maintains the suspense effortlessly. Lang reveals the methods of the spies with meticulous care.... The film is spiced with touches of humor, and includes a brief segment in an Expressionist style.... Lang's editing virtuosity is very much in evidence. Of particular interest are his use of inserts; photographs, notes, and especially the intertitles which have an exact corresponding effect with the way sound matches are used in The Testament of Dr. Mabuse. Spies was made by Lang's own production company, which explains the differences from the more lavish effects and sets in his previous films.” --Prof. Bertrand Augst