A shadowy fiend called the Avenger is committing murders in London, telephone operator Daisy (Elizabeth Allan) has actually heard one of the victims just before she was offed. Meanwhile the slightly strange foreign musician Angeloff (Ivor Novello) has taken up as a lodger with Daisy's parents...
As Angeloff is rather mysterious and enigmatic (though this is laid on a bit thick) and Daisy takes a bit of a shine to him the family begin to suspect he is the Avenger though that may be more to do with the fact Daisy fancies him...
While quite atmospheric the story is rather plodding and at times a bit hard to follow, the dialogue in this early talkie sometimes a bit muffled. An interesting if not great film with some indifferent acting at times. However it is worth watching for Novello who also played the same role a few years earlier in Hitchcock's silent movie of the same story. Jack Hawkins also makes one of his earliest film appearances.