“No mistake at all, corporal.  I lifted it.  It is a long, heavy ladder,—­over twenty feet, I should say.”

“There is such a ladder back there, captain,” said the sergeant, “but it always hangs on the fence just behind the young officers’ quarters,—­Bachelors’ Row, sir, I mean.”

“And that ladder was there an hour ago when I went my rounds,” said the corporal, earnestly.  “I had my hurricane-lamp, sir, and saw it on the fence plainly.  And there was nothing behind the colonel’s at that hour.”

Chester turned away, thoughtful and silent.  Without a word he walked straight into the quadrangle, past the low line of stone buildings, the offices of the adjutant and quartermaster, the home of the sergeant-major, the club and billiard-room, past the long, piazza-shaded row of bachelor quarters, and came upon the plank walk at the corner of the colonel’s fence.  Ten more steps, and he stood stock-still at the head of the flight of wooden stairs.

There, dimly visible against the southern sky, its base on the plank walk below him, its top resting upon the eaves midway between the dormer-window and the roof of the piazza, so that one could step easily from it into the one or on to the other, was the very ladder that half an hour before was lying on the ground behind the house.

His heart stood still.  He seemed powerless to move,—­even to think.  Then a slight noise roused him, and with every nerve tingling he crouched ready for a spring.  With quick, agile movements, noiseless as a cat, sinuous and stealthy as a serpent, the dark figure of a man issued from Alice Renwick’s chamber window and came gliding down.

One second more, and, almost as noiselessly, he reached the ground, then quickly raised and turned the ladder, stepped with it to the edge of the roadway, and peered around the angle as though to see that no sentry was in sight, then vanished with his burden around the corner.  Another second, and down the steps went Chester, three at a bound, tip-toeing it in pursuit.  Ten seconds brought him close to the culprit,—­a tall, slender shadow.

“You villain!  Halt!”

Down went the ladder on the dusty road.  The hand that Chester had clinched upon the broad shoulder was hurled aside.  There was a sudden whirl, a lightning blow that took the captain full in the chest and staggered him back upon the treacherous and entangling rungs, and, ere he could recover himself, the noiseless stranger had fairly whizzed into space and vanished in the darkness up the road.  Chester sprang in pursuit.  He heard the startled challenge of the sentry, and then Leary’s excited “Halt, I say!  Halt!” and then he shouted,—­

“Fire on him, Leary!  Bring him down!”

Bang went the ready rifle with sharp, sullen roar that woke the echoes across the valley.  Bang again, as Leary sent a second shot after the first.  Then, as the captain came panting to the spot, they followed up the road.  No sign of the runner.  Attracted by the shots, the sergeant of the guard and one or two men, lantern-bearing, came running to the scene.  Excitedly they searched up and down the road in mingled hope and dread of finding the body of the marauder, or some clue or trace.  Nothing!  Whoever he was, the fleet runner had vanished and made good his escape.