Greson started from where the carriage had entered the city.
The young gymnast went to the exhibition grounds and attempted to trace up the man who had fired the shots at the balloon.
From one and another the young gymnast was able to trace up Porler to a third-rate boarding-house on one of the side streets.
He was about to enter the place when he saw a fellow named Danny Murphy, who was Porler’s assistant, leaving in a great hurry.
“Perhaps he is going to join Porler at some place where Mart is being kept,” said Leo to himself. “I’ll follow him.”
And follow Murphy he did.
All unconscious of being watched, Porler’s tool walked half a dozen blocks until he came to the residence in which Mart was kept a close prisoner. He walked around to the rear through an alleyway.
Close behind him, Leo heard him give a peculiar knock on the door.
A moment passed and Murphy was admitted. The back door was locked and bolted after him.
When the door had been opened Leo had caught a momentary glimpse of Porler’s face.