The resulting film was the most accomplished he had yet made, demonstrating an astonishing command of and inventiveness with the infant medium of sound film. Working within the suspense genre for which he had shown such aptitude in The Lodger, for his source material this time Hitchcock turned to a play by Charles Bennett (who would become of one the director's most valuable collaborators later in the 1930s), and handled the task of adapting the script himself. Blackmail established the model for many of the themes, techniques and plot devices that Hitchcock would return to again and again in his mature work.
Like many early talkies, Blackmail was produced simultaneously in both sound and silent versions. There is the opinion in some quarters that the silent version is the superior one, an expression of "pure cinema" unencumbered by the restraints of the newfangled commercial sound film technology. The silent version is certainly effective enough, but a comparison of the two versions reveals that Hitchcock used the new creative possibilities afforded by sound -- specifically, its ability to heighten the tension between what we see and what we hear -- in order to create a more fully-realized and satisfying suspense film.
Because Hitchcock would soon develop these techniques and ideas to a greater degree, beginning just a few years later with The Man Who Knew Too Much and The 39 Steps, Blackmail can appear, in contrast with those classics, to be a quaint work primarily of historical interest as an early, formative effort from a great director who would go on to do much better things. In some ways, to be sure, it is that. But to view the film this way does a disservice to the inventiveness and creativity, and indeed the apparent ease, with which Hitchcock adapted his style to the new sound film medium. In that context, Blackmail remains an remarkable achievement, and one of the most important films the director ever made.