determined on the boldest and the riskiest move he could
have made. But it was also the safest. Instead of striking out at
once for the shore, he slipped around behind the motor boat, and clung
to the stern as it swept along, clear of the propeller, but hidden by
the shadow from the overhanging stern.

At the same moment there was a sudden outburst of shouts from the
shore, and where all had been silence and darkness lights sprang out
and the forms of excited, running men and boys appeared.

The headlight of an automobile was suddenly thrown on the scene, and
Jack, guessing who was there, called out that he was safe and in the
water.

"Swim ashore, Jack," shouted Dick Crawford's welcome voice, and a
moment later, all fear of his captors gone now, Jack was helped up the
steep bank.

"We got them in a trap," cried Dick Crawford. "I figured they'd have
to come this way. They can't turn around, and the gate of the lock is
closed against them at the river end. They're bottled in here, and
they can't escape, no matter which way they turn."

In the power boat the big man who had carried Jack off was standing up
now, cursing volubly, and trying to see what lay ahead of him. But it
did not take him long to see and realize that all hope of escape in
that direction was cut off. The boat had come to a full stop, and he
looked about him in desperation, his mask on his face again. He held a
revolver in his hand, but, for some reason, he did not fire.

"Careful, fellows!" cried Dick Crawford. "He's got a gun there, and
you can't tell how soon he'll begin shooting."

"Not very soon, Dick," said Jack Danby, with a laugh. "He left his gun
within reach of me, thinking I was still senseless, and I took all the
cartridges out. There was a box half full of cartridges and I dropped
that overboard, too, so I guess his teeth are drawn unless one of them
has another gun."

"Good work, Jack! He'd find it hard to hit any of us, but it's good to
think he can't even try, anyhow. You surely had your nerve with you to
think of that."

"I had to, Dick. I was going to make a break for it here in the lock,
anyhow, and I didn't want him to be able to take a shot at me from
behind while I was trying to climb up to the shore. It would have been
too easy for him to hit me, and from the way he talked there's nothing
he'd like better than to use me as a target."

Suddenly the roar of the boat's engine broke put again.

"What's he t