The
submarine boy found himself at the street-end of a narrow alley between
two brick buildings.

"He has gone into the rear house, at the end of the alleyway," decided
Benson, peering down this narrow thoroughfare. "He has left the door
partly open, too. I'll have to have a look-in."

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