So rapt was I in the sympathetic contemplation of her that I did not see Maitland’s entrance or realise I was observed till he plucked me by the coat and motioned me to get down.  I did so and he told me he had rented the rooms, and laid before me the plan he meant to pursue.

As soon as he had ceased speaking I said to him:  “George, you are undoubtedly on the right track.  The man in there is the one we are looking for, fast enough, but I am afraid we are a bit too late.”

“Too late!” he exclaimed in a tone that I feared might be overheard.  “What the mischief do you mean?”

“I mean,” I replied, “that M. Godin is already upon the scene.”

In the next ten seconds Maitland turned all colours and I edged nearer to him, expecting him to fall, but he did not.

“M.  Godin!” he ejaculated at length.  “How in the name of all the gods at once—­Doc, he’s all they claim for him, and as fascinating as he is clever;” at which last remark a heavy cloud passed over Maitland’s face.  “Come,” he continued listlessly, “you may as well tell me all you know about it.”

I then confided to him what I had heard and ended by asking him what he proposed to do.

“Do?” he replied.  “There is but one thing I can do, which makes the choice decidedly easy,” and he set his jaws together with a determined expression, the meaning of which I knew full well.

“I shall camp right here,” he said, " till I learn all I wish to know of our neighbours yonder.  I have already provided myself with instruments which will enable me to note every movement they make, indeed to photograph them, if necessary, and to hear and record every word they utter.  You look surprised, but it is easily done.  I will place my lenses there at the chink through which you were gazing and bring the image down into my camera obscura by a prism arranged for total internal reflection.  As for the hearing, that is easier yet.  I will carefully work away the plaster on this side to-night till I get through to the paper covering their wall.  This I will leave intact to use as a diaphragm.  I have then only to fasten my carbon to it, and, behold, we have a microphone or telephone—­whichever you choose to call it.  All I have to look out for is that I get it high enough to avoid the danger of the paper being accidentally broken from the other side, and that I work quietly while removing the plaster.  I shall, of course, cover it with a bit of black felt to prevent our light from showing, and to deaden any sounds from this side.  This will enable us to hear all that goes on in the other room, but this may not be enough.  We may need a phonographic record of what transpires.