Her Majesty's Minister by William le Queux

So swiftly did the figure disappear from the doorway of the patisserie that I doubt whether the elegant woman there seated had been aware of his presence. She was sitting with her face half turned from the door, and, unless by means of the mirror, she could not possibly have witnessed his sudden hesitation and disappearance. That he intended entering there, and had been prevented by her presence, was manifest. He had no desire to be seen by her, that was quite evident.

Again it seemed as though Yolande's mysterious correspondent was actually this man, whose presence in Paris had caused her so much anxiety.