I little relished the prospect of waiting in that swamp-like spot, but since no alternative presented itself I accepted the inevitable.  For close upon an hour we stood watching the red window.  No sound of bird, beast, or man disturbed our vigil; in fact, it would appear that the very insects shunned the neighbourhood of Hassan of Aleppo.  But the red light still shone out.

“We must risk it!” said Carneta steadily.  “There are French windows opening on to that verandah.  Ten yards farther around the bushes come right up to the wall of the house.  We’ll go that way and around by the other wing on to the verandah.”

Any action was preferable to this nerve-sapping delay, and with a determination to shoot, and shoot to kill, any one who opposed our entrance, I passed through the bushes and, with Carneta, rounded the southern border of that silent house and slipped quietly on to the verandah.

Kneeling, Carneta opened the knapsack.  My eyes were growing accustomed to the darkness, and I was just able to see her deft hands at work upon the fastenings.  She made no noise, and I watched her with an ever-growing wonder.  A female burglar is a personage difficult to imagine.  Certainly, no one ever could have suspected this girl with the violet eyes of being an expert crackswoman; but of her efficiency there could be no question.  I think I had never witnessed a more amazing spectacle than that of this cultured girl manipulating the tools of the house breaker with her slim white fingers.

Suddenly she turned and clutched my arm.

“The windows are not fastened!” she whispered.

A strange courage came to me—­perhaps that of desperation.  For, ignoring the ominous circumstance, I pushed open the nearest window and stepped into the room beyond!  A hissing breath from Carneta acknowledged my performance, and she entered close behind me, silent in her rubber-soled shoes.

For one thrilling moment we stood listening.  Then came the white beam from the electric lamp to cut through the surrounding blackness.

The room was totally unfurnished!

CHAPTER XXXI

THE POOL OF DEATH

Not a sound broke the stillness of the Gate House.  It was the most eerily silent place in which I had ever found myself.  Out into the corridor we went, noiselessly.  It was stripped, uncarpeted.

Three doors we passed, two upon the left and one upon the right.  We tried them all.  All were unfastened, and the rooms into which they opened bare and deserted.  Then we came upon a short, descending stair, at its foot a massive oaken door.

Carneta glided down, noiseless as a ghost, and to one of the blackened panels applied an ingenious little instrument which she carried in her knapsack.  It was not unlike a stethoscope; and as I watched her listening, by means of this arrangement, for any sound beyond the oaken door, I reflected how almost every advance made by science places a new tool in the hand of the criminal.