Das grüne Monokel (1929)

The young Hans von Traß is a high-ranking German diplomat. One day, an important secret document is stolen from the Legation Councillor. Oddly, his fiancée, Christa Varell, who was lured to Hamburg with a forged letter, writes a letter accusing herself of the theft. Master detective Stuart Webbs is assigned this strange case by von Traß’s superior—but is it really Webbs? No: it is the document thief himself, a certain McCornick, who has equipped himself with Webbs’s papers, stolen by an accomplice from the real detective, and has even acquired a green monocle, which the real Stuart Webbs has been wearing for some time. Deeply distressed by the document theft, von Traß meets the real Stuart Webbs while travelling. Webbs is willing to take on the case and quickly discovers that Christa’s self-incriminating letter is a forgery. Webbs learns that McCornick is behind the theft—a shadowy figure who belongs to a foreign criminal gang. McCornick has an ally in Inez Rion, his lover and a rather disreputable dancer, as well as in the two petty crooks Miller and Snyder, two of his henchmen. While Inez tries to cover up all traces of the theft as best she can, Stuart discovers that she is actually the one who wrote the false confession. Webb forces Inez to confess and then pursues McCornick by express train, car, airplane, and motorboat. The chase takes him all the way to Montreux. There, the crook briefly manages to outwit him once more. McCornick shoots a henchman whom he feels has betrayed him. Then a fierce shootout breaks out between the real and the impostor Stuart Webbs. At last, the master detective brings the gang down and has them arrested. Legation Councillor von Traß gets his important document back.