night. It was overcast and starless, and it was
impossible under any condition to see more than a few yards about them.

Suddenly Rob clasped Merritt's arm with a grip that made the other lad
wince.

"Look! Look there!" he cried. "Off there. It's gone now. It only showed
up for an instant."

"It's your turn to be nervous," rejoined Merritt; "blessed if I saw
anything!"

"My eyes must be as sharp as your ears, then. I'd swear I saw a shadowy
thing sneak away from us across the water."

"What sort of a thing?"

"A boat. I only saw it an instant, of course; but I'm sure I wasn't
mistaken."

"You think that somebody in that boat was monkeying with the
_Peacemaker_?"

"That's the only reasonable explanation."

"But what could they have been doing?"

"That remains to be seen; but it's our duty to try to find out."

"What's your plan?"

"Well, that scraping noise appeared to me to come from the under side of
the hull."

"Yes."

"Then that's the place to look for mischief."

"But how are you going to get at it?"

"Dive over and feel around at about the place where we heard the sound."

"That was on the port side and apparently right under the cabin floor."

"Then that's the place to look."

As he spoke, the young leader of the Eagles stripped off his shirt, for
the night was warm and he was coatless, and then divested himself in
turn of his shoes and trousers.

This done, he turned to Merritt.

"I don't know just why, old fellow," he said, "but I've got an idea in
my head, somehow, that there's some sort of dirty trick being put up
to-night."

"What do you mean?"

Merritt asked the question looking into his comrade's eyes as he clasped
Rob's extended hand. For some reason he felt a cold shudder run through
him. What the danger was that Rob dreaded he did not know, but there
was something in the hand-shake that his leader gave him that almost
seemed like a farewell clasp.

Before his inquiry was fairly out of Merritt's mouth, Rob had disengaged
his palm and slipped silently over the side of the submarine. As the
waters closed above him, Merritt almost cried out aloud. The same
mysterious sense of a danger, terrible and imminent, had run through his
brain like a warning flash. But it was too late to recall his comrade
now.

Whatever peril Rob was facing, he was called upon to brave it out alone.

* * * * *

Earlier that evening a small, but fast and high-powere