As he stole down the alley-way Jack Benson was too sensible, and by this time, too much experienced in the ways of a rougher world, not to suspect that there might be some trap in that door partly open.  “He may have seen me, and may have left that door open on purpose,” Benson reflected.  “He may be lying in wait for me, inside.  Or else he may have left that door open, just to make me suspect a trap and keep out.  In the meantime, he may be slipping through a door on the other side of the house, and sneaking away from me.”

For a few seconds Jack Benson paused thoughtfully on the step just outside the door that was partly ajar.

“I may walk into a trap, by going inside, or I may be letting that wretch walk out of one by staying out here,” wavered Benson, torn between two impulses.

Then, just as suddenly, this thought flashed through his mind: 

“What you’re doing is for the Flag!  Never mind what happens to you, Jack Benson.  Just rash in and say ’here goes’!”

There was not another second’s hesitation.  Jack Benson softly pushed the door far enough open to admit him.  At the back of the hallway he saw stairs leading below.

“Basement stairs, with a rear basement door letting out on another alleyway!” suspected the submarine boy.

Though he had determined to be as reckless as seemed necessary in order to get quickly on the trail of the vanished one, Jack moved on tip-toe.  He had all but reached the head of the stairs when a ground-floor door behind him opened noiselessly.  The long-legged one, who had an equally good reach of arm, thrust out a noose that fell over the boy’s head.

“Ug-g-g-gh!” rattled in Jack Benson’s throat, as Millard, in grim silence, jerked the rope noose tight about the boy’s neck.  A sharp pull, a twist, and Millard had the boy face down in that hallway, and was kneeling on the victim’s back.

“You ought to have known enough to keep away from me,” growled the wretch, as he tightened on the noose.

That was about the last that the young submarine captain heard or knew, just then, for things were rapidly growing black before his eyes.  Jack tried to fight, but the choking was too severe.  He couldn’t get even a breath of air into his lungs to give him fighting strength.

Finding that the boy’s struggles had ceased, the long-legged one eased off on the noose.  He bent Jack’s arms behind him so that the wrists crossed.  Then, pulling another cord from one of his pockets, the wretch tied the youngster’s hands with a few deft movements.  Oh, but this rascal was an expert artist with ropes and cords.

Jack felt himself being prodded just over the pit of the stomach, and his senses slowly wandered back to him under the disturbing handling.  He was lying on his back, when his eyes opened once more.  His throat felt sore, but he could breathe again.

Then the submarine boy discovered that his hands and feet were securely lashed.  Beyond that, he discovered Millard squatting on the floor, close by, in Japanese fashion, for the foreign agent was sitting back on his own crossed heels.