regardless of Bob's advice.

"I don't know, but I don't see why he should shoot one of his own gang."

"He blew up Mr. Wernberg though."

"I know it, but I can't understand it, and as I said I don't think we
ought to talk here."

They proceeded in silence. Both boys were eager to join the others and
they wondered what they could be doing down by the river. Perhaps they
had captured the plotter and had dispatched Karl for rope or handcuffs
to secure him. At any rate nothing suspicious had happened since the
shots had first been heard.

The boys had progressed but a short distance further, when suddenly a
great tongue of flame shot heavenward between them and the river. An
ear-splitting detonation followed, and the very earth was rocked by an
enormous explosion. Both boys were thrown violently to the ground by the
force of it, while showers of earth, bricks, and material of all kinds
pelted down all about them.

A moment later the boys were on their feet, still partly stunned and
undecided as to whether they should run or not.

"There may be another one coming," warned Hugh.

While they hesitated a man suddenly appeared running swiftly away from
the direction of the explosion.