The Russian Cipher
Written by
Huan Mee
Copyright 1899
Published in Cassell's Magazine, June 1899. Reprinted in Espionage Magazine, May 1987. Collected in the next year.
Madame Lerestelle is asked personally by France's Premier Rochè to investigate how secret messages between him and the Russian Ambassador, Count Zarfine, have been intercepted, opened, decrypted, and then resealed, causing the intel inside regarding confidential negotiations to become known.