What I enjoy about the opening of M is the fact it uses many techniques of the German Expressionism movement. Using the lighting to contrast the action, the long flowing shots, long takes in the action, the absence of light. When our "man in black" shows up, you feel that sense of dread, because you know what will most likely happen, and the fact you can't see who it is, just a shadow. What's more horrifying, knowing the cat knocked over something, or hearing that random bump in the night in a dark house? That notion is reflected here with our man in black. A great opening!