This letter had been stopped in transit in France a few days after the entrance of the United States into the Great War. There seemed to be some small hope of finding a clue to the author through advertising it as an undelivered letter. While this plan was under contemplation, however, a report reached headquarters, from an operative, to the effect that while soliciting Y. M. C. A. subscriptions in a St. Louis office building late at night, he had surprised a citizen of German origin, alone in his office, who appeared to be attempting to decipher a letter with the aid of two books, seemingly code books. The letter was then advertised and two operatives were assigned to watch the appropriate window at the General Post Office. After a week’s vigil, the clerk in charge beckoned to the operatives and pointed to the retreating figure of a woman of small stature, almost wholly enveloped in a black shawl, and informed them that she had inquired for the Bernkong letter. She had said that she was not the author but would be glad to pay any additional postage necessary to send it on its way. In the course of this explanation the woman had left the building and was lost in the crowd on the street. It therefore became necessary to continue the surveillance at the Post Office in the hope of the woman’s return. Within a week she did reappear, late in the afternoon, and inquired for mail under the name of a Catholic Sister. It was learned that she had been receiving mail under this name for a considerable length of time. She was followed for a number of blocks and was seen to enter a large institution conducted as a girls’ rooming house. A woman operative of the St. Louis Division, American Protective League, that night, carrying a suit case, applied at the institution for a room, explaining that she had just arrived from a nearby city. She had a detailed description of the woman, but for a period of more than three weeks she was unable to find anybody in the place fitting the description. This woman operative was then also assigned to the Post Office, where, in due time, the woman reappeared.