This was an excellent pre-code mystery which cried out for a series starring the dapper, cosmopolitan Robert Montgomery. Could have been a second-story-man-turned-detective, or something along those lines. Always thought he had a charismatic presence on screen which commands your attention, and charisma is an elusive quality; either you have it or you don't.
He is paired here with Elizabeth Allan (not his wife, but same name) and there is a great deal of chemistry between the two (funny how important an ingredient it is to a successful picture). A sentence or two about the plot; Someone is killing bobbies in and around London, much to the chagrin of Scotland Yard. As another cop murder is taking place on the street, RM is stealing a precious diamond in an adjacent mansion. As he jumps out a window, he lands on the dead policeman, bloodying his gloves in the process. He leaves them at the scene - seemingly The Yard's first clue. For the rest of the picture he tries to extricate himself from the murder while hanging on to the stolen diamond.
Things go somewhat awry towards the end - apparently, the screenwriter was stuck for an ending and opted for one of convenience and unbelievability, but the picture was so good up to that point I decided to go with it and suspend disbelief. It was easy, as it is such an enjoyable movie.