made the night noisy. Those people were late risers and they went
to bed late as well. There was a dance at the hotel, and it was well
attended. So the sharp beat of the engines of the little boats
disturbed those who were trying to sleep. Jack was so tired, too, that
it was hard for him to get to sleep.

He kept thinking of everything that had happened at Haskell Crossing,
and of the desperate minutes in which, while he knew the fate that was
in store for the onrushing train, he had been powerless to prevent the
catastrophe that threatened. And then suddenly, while he was half
asleep and half awake, he remembered something that had escaped him
before, something he had seen and that had been recorded in his brain,
although it was only now that the picture stood out vividly and with
meaning.

There had been three men in the room with Hank Hudson and Tom Binns
while he had waited at the window and spied upon them. And three men
had returned, after he had seized the chance to give the warning that
had saved the train. But they were not the same three. He remembered
now, with a sudden flash of clear understanding that one of the three
had been a stranger--that of the three who were caught, one was a man
he had not seen before.

He started up in his blanket.

"Then there _were_ four of them!" he cried, half aloud. "And one of
them is free, and able to plan new deviltries. I wish they'd caught
them all!"

But even that thought, disturbing as it was, did not keep him awake
much longer. As he lay there, his tired body resting with the very act
of lying down, he grew gradually more drowsy, and he drifted off asleep
at last with the humming of a power boat on the lake beating against
his ears.

He slept a long time. The camp was quiet. In the distance an owl
hooted now and then, and until long after midnight the sounds of
activity persisted on the lake. The moon had risen early, and was
setting soon after midnight, so that it was very dark under the trees,
though out on the lake, once the shadow of the trees around the shore
was passed, the stars gave abundant light. And, because he was so
tired, and trusted so entirely to the sentries, Jack had no thought of
watchfulness when he fell asleep, and slept more heavily than was usual
with him when he was in camp with the Scouts.

The sentries were posted on all sides of the camp, as a rule, but no
one had foreseen the need of any watch on the side of the camp