Red Finger — Spy Poison!

Written by Arthur Leo Zagat

Copyright 1936

Published in Secret Service Operator #5 v7 #2, Jun-Jul 1936. Reprinted in the collections The Hand of Red Finger and Second Hand Death.
"A crusty dowager whispers to a second-hand bookseller and Red Finger, the terror of spydom, follows a perilous trail to death — and romance!"