Acoustic Anchor

My clawed boots advanced into the hollow barrel of the right conduit as darkness deepened. The concrete floor ended at a dry expansion joint where a loose iron masonry anchor hung tilted inside an old drilled hole. Any draft from above set the threaded steel sleeve humming against the stone wall. I crouched in absolute stillness, unsheathing my wrist blade. Inserting the tapered steel edge into the fastener's split collar, I levered the sleeve outward until its ridged teeth bit deep into the concrete casing. The shudder ceased into complete silence. A low click rattled in my throat. I settled against the cold invert to watch.