Secret Agent dallies much on the way but rates as good spy entertainment, suave story telling, and, in one particular case, brilliant characterization. This is the role of the ‘Mexican’, a hired killer as played by Peter Lorre. Director Alfred Hitchcock has done well at lending the tale’s grim theme [from the play by Campbell Dixon, based on the novel Ashenden by W. Somerset Maugham] with deftly fashioned humor, appropriate romantic interplay and some swell outdoor photography.
More critical element will find the part of Madeleine Carroll somewhat straining credulity. The film has her philandering at the game of espionage and out of sheer ineptitude pulling one of the major coups of the service. Likewise unconvincing is the overly sensitive conduct in which her co-spy (John Gielgud) indulges once he is bitten by love.
Production maintains an easy-going pace almost throughout, with most of the action cast against the background of the Swiss Alps. Gielgud is assigned to Switzerland to prevent a German spy from getting back into pro-German territory. To do the actual killing, Lorre, a Mexican with a juvenile sense of fun but a boundless enthusiasm for playing the knife upon humans, is sent along. Arriving on the scene, Gielgud finds that Carroll had been matched with him for the job, with the pair to pose as man and wife.