Maybe this fellow has been spying about. May be going to report to a
German submarine out there some place."

"Think we had better follow and have a look?" asked Jack.

"Believe it would be a good idea. Let's go."

Without another word, Jack brought the boat about and headed after the
one that had so recently dashed by them. In the darkness ahead there was
nothing to be seen.

"Like looking for a needle in a haystack," Jack called to Frank.

"That fellow can't be up to any good," declared Frank. "He showed no
light and was going in a terrible hurry. There's something up."

"Does seem that way," agreed Jack.

"Say! Is this as fast as this thing can go?" demanded Frank. "We won't
ever get any place this way. Let her out a bit."

Jack did so and the little boat seemed literally to fly over the dark
water. This terrific speed Jack kept up for some time and then slowed
down.

"We'll bump into something at this rate," he said; "and that would
settle the whole business. We must be cautious."

"Cautious!" repeated Frank. "We won't find that German being cautious."