and thus unable to elude us, whichever way she turned upon leaving the window.  We had previously planned how we should shadow our quarry, one on each side of the street in order not to attract attention, but these tactics seemed to be entirely unnecessary, for the young lady did not have the slightest suspicion that anyone could be in the least interested in her movements.  She walked leisurely along, stopping now occasionally to gaze at the shop windows and never once turning to look back.  She did not even conceal the letter, but held it in her hand with her porte-monnaie, and I could see that the address was uppermost.  A strange sensation came over me as I dogged her steps.  I felt as an assassin must feel who tracks his victim into some lonely spot where he may dare to strike him.  It was useless for me to tell myself that I was on the side of justice and engaged in an honourable errand.  A single glance at the girl’s delicate face, as frank and open as the morning light, brought the hot blush of shame to my cheek.  In following her I dimly felt that, in some way, I was seeking to associate her with evil, which seemed little less than sacrilege.  I could do nothing, however, but keep on, so I followed her through Devonshire Street, to New Washington and thence down Hanover Street almost to the ferry.  Here she turned into an alleyway and, waiting for Maitland to come up, we both saw her enter a house at its farther end.

George glanced hastily up at the house and then said, as he seized me impatiently by the arm:  “It’s a tenement house; come on, the chase is not up yet; we, too, must go in!”

So in we went.  The young lady had disappeared, but as we entered we heard a door close on the floor above, and felt sure we knew where she had gone.  We mounted the stairs as noiselessly as possible and listened in the hall.  We could distinguish a woman’s voice and occasionally that of a man, but we could not hear what passed between them.  On our right there was a door partly ajar.  Maitland pushed it open, and looked in.  The room was empty and unfurnished, with the exception of a dilapidated stove which stood against the partition separating this room from the one the young lady had entered.  Maitland beckoned to me and I followed him into the room.  There was a key on the inside of the door which he noiselessly turned in the lock.  He then began to investigate the premises.  Three other rooms communicated with the one of which we had taken possession, forming, evidently, a suite which had been let for housekeeping.  Everything was in ill-repair, as is the case with most of the cheap tenements in this locality.  The previous tenant had not thought it necessary to clean the apartments when quitting them,—­for altruism does not flourish at the North End,—­but had been content to leave all the dirt for the next occupant.