The Shoes under the Curtain
In this guise, Nyarlathotep is only ever visible as a pair of well made formal men’s shoes of some dark leather peeking out from under a curtain and a careful listener may listen in on what appears to be at least one half of a conversation hinting at terrible secrets that yet are never fully revealed without catching the other half. If the curtain is drawn away or one looks behind it, there is no one there.