The part of the palace in which this apartment was situated formed the extremity of an architectural wing, which was fronted at the distance of about a hundred feet by a second wing equal in length to the first and parallel with it. These two wings formed with the main structure the three sides of a court. As he casually turned his eyes upon the opposite wing, at the point where it formed an angle with the main building, Paul thought he detected a movement on the part of somebody or something about half-way between the roof and the ground. Straining his eyes to the utmost, he became convinced that what he saw dimly outlined against the gray wall was the figure of a man poised in mid-air; for as Paul could detect no ladder beneath him, he could only come to the conclusion that the fellow was suspended by a rope. The man made no attempt to ascend or descend, but continued in the one position; and as far as Paul could discern in the darkness his arm was moving to and fro with horizontal motion. Now just at the place where this man hung there was, as Paul had observed earlier in the evening, a small window, a window crossed by iron bars. A grated window in a palace suggests the idea that the room thus secured is used for the preservation of things valuable; at any rate this was Paul's idea. He believed that the fellow was quietly removing the iron bars with the view of procuring whatever it was that lay behind them. It was an extremely hazardous enterprise. True, the man was favored by the darkness, and by the noise of wind and rain, but at any moment he was liable to be surprised by the night-watch going its rounds, either in the courtyard below or on the roof above. Two sentinels paced the very battlements overlooking this court. Earlier in the evening Paul had heard their footsteps overhead and their challenges. Were they asleep? If not, they must be keeping a very lax watch to permit this man to perform such work under their very eyes. Then the truth flashed upon Paul. The man himself was a soldier, one of the two appointed to patrol this particular part of the roof. The other was his confederate. Both were engaged in some nefarious work. Treason was afoot in the palace! Rejecting his first impulse, which was to steal quietly downstairs and summon the guard, Paul resolved to tackle the two single-handed. As there was no staircase from his room to the roof, he determined to mount to the battlements by means of a water-pipe adjacent to his window. Thrusting a loaded pistol within his breast, he stepped out upon the window-sill, and pulling himself up by the water-pipe silently and quickly, he clambered over the battlements without detection. Keeping within an embrasure, he peered out along the roof. There, a few yards distant, outlined against the sky, was the tall, cloaked figure of a sentinel leaning upon his rifle and with his eyes turned towards the grated window.