The Shadow of the Wolf by R. Austin Freeman

FOR the second time, in connection with the death of Daniel Purcell, Mr. Varney found it necessary to give an attentive eye to the movements of the postman. He had ascertained from the post office the times at which letters were delivered in the neighbourhood of Margaret's flat; and now, in the gloom of a December evening, he lurked in the vicinity until he saw the postman approaching down the street and delivering letters at the other flats on his way. Then he entered the now familiar portals, and made his way quietly up the stairs until he reached Margaret's outer door. Here he paused for a few moments, standing quite still and listening intently. If he had been discovered he would have simply come to pay a call. But he was not, and the silence from within suggested that there was nobody in the hall. With a furtive look round, he drew a letter from his pocket and silently slipped it into the letter-box, catching the flap on his finger as it fell to prevent it from making any sound. Then he turned and softly stole down the stairs; and as he reached the ground floor the postman walked into the entry.

It was not without reluctance that he came away. For she was behind that door, almost certainly -- she, his darling, for whose freedom from the imaginary shackles that she wore he was carrying out this particular deception. But his own guilty conscience made it seem to him that he had better not be present when the fabricated letter arrived. So he tore himself from the beloved precincts and went his way, thinking his thoughts and dreaming his dreams.