Hitchcock's last silent film, Blackmail was also his first sound effort—and one of the first British "talkies" as well. A resounding popular and critical success, Blackmail prefigures some of the director's most famous themes and demonstrates techniques for which he would be noted.
It started out as a silent film and was converted to sound during filming. Both silent and sound versions are available, the silent version being released because most British theaters at the time weren't equipped for sound. The Chief Inspector is played by a different actor in the sound version than in the silent. The sound version is embedded below::
Variety says it "is most draggy" and "has no speed or pace and very little suspense." The New York Times says in a review from the time of its release, "Altogether, one gathers the impression that "Blackmail" may possibly not make such a strong appeal to the general public as it deserves to because of its artistic qualities." TCM has an overview. The British Film Institute has an article on the silent/sound filming and an overview and some video clips. The BFI says,
Blackmail displays many of the stylistic elements and themes with which Hitchcock would come to be associated: particularly a fascination with male sexual aggression and female vulnerability.Rotten Tomatoes gives it a score of 89%.