Edgar Wallace wrote over 200 thrillers and so it is little surprise that many elements are used time and again.We have a gang terrorising London,with a mysterious leader known to nobody.Anyone who refuses their demands for payment of a substantial sum is murdered, often in unusual circumstances.However the point is that if you have seen many of the films of his books,then the gang leader stands out a mile.This film was clearly a quota quickie made for Universal films by Reginald Denham who doubled as a film and theatre director in the 30s.He keeps the action moving along and has used his presumably minuscule budget well.Alfred Drayton is unusually cast as the Scotland Yard detective.However this film is not nearly as good as "The Frog" starring Gordon Harker.