time, but slowly and carefully picking their way. They skulked along in
the shadow of the factory walls, ready for any emergency that might
arise. They kept close together and if the truth were known both boys
would have been very glad to have had an armed companion with them.

They had covered perhaps a hundred and fifty feet or so, and ahead of
them could just make out the dark bank of the river. Suddenly they saw a
man appear around the corner of the building, running toward them. Bob
and Hugh crouched against the brick wall and waited for him to come
near. All at once Bob recognized the stranger and started forward.

"Karl," he cried.

The man halted.

"Where are you going?" asked Bob. "Where are father and the others?"

"Down by the river," replied Karl and once more broke into a run. A
moment later he was lost to sight in the darkness.

"Seems to me he's in an awful hurry," remarked Hugh.

"Father had probably sent him on an errand," said Bob. "Let's hurry and
see if we can't find father and Sergeant Riley."

"Who do you think shot Lena?" asked Hugh.

"I don't know. We'd better not talk here now."

"Do you suppose it could have been the fake detective?" said Hugh