"That's so," agreed Rob; "tell you what, Merritt, it's up to us to investigate."
"Yes, let's go on deck and see what we can find out."
Together the two lads climbed the steel stairway leading to the conning tower, and presently emerged on the rounded steel back of the diving craft. They stood here for a minute or two, trying to get their eyes used to the sudden change from the bright light of the cabin to the inky darkness of the 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?"