the establishment in the alley to which morden led professor zender was in no wise advertising itself to passers by. a dirty window below street level emitted no light, and the stout door at the bottom of a set of iron steps could barely be distinguished from the brick wall.
the professor waited on the street level as morden descended the steps and rapped on the door, three times, then two. not, the professor thought to himself, the most unbreakable code.
presently the door opened, barely emitting light into the stepwell. morden entered, and held the door open while the professor carefully descended the steps, feeling in front of himself with his stout stick.
whoever had opened the door for morden had apparently gone on ahead, and the professor and morden navigated the low gloom - gentle reader , is there ever any high gloom? - forgive the digression - but then, is not digression the soul of narrative? - but i digress.