The Detective Tales cover for June

This is again this time of the month when I upload a cover from Detective Tales and comment on it. I have chosen an odd one this time, from June 1936. I say odd one because it has a villain literally leashing out of a bookshelf, while the damsel in distress jumps away from him. The hero is gunning away at an unknown adversary, a common trope in pulp magazines, at least in Detective Tales. His shirt is teared apart on his left arm. What strikes me about the this cover is of course the mustachioed villain showing up like a jack-in-the-box from a hidden door/secret passage. Not so much how he looks like, he looks like a a stereotypical elegant villain, or what he is trying to do, grabbing the heroine (does he want to hold her to death?), but where he comes from, or rather what camouflaged the secret door. A bookshelf. Maybe I am reading too much into it, but I find it a nice little mise en abyme, evil jumping off the books.