"Fall back and mount, fellows," said Elmer; "and you, Lil Artha, keep listening for the signal to wait for us. Only a mile do we dare keep going; to get closer to the place of ambush might betray us, as they would hear the explosions from one of these machines, the muffler of which never works decently. Get that?"
"It's as plain as the nose on my face, and nobody can miss that," replied the other, as he started off along the road.
Elmer cautioned his comrades to make as little racket as possible, and presently they followed on their motorcycles.
About ten minutes later a low, weird sound floated through the air. To most persons it would have meant that some farmer's watchdog was uneasy, and baying at the stars; but Lil Artha knew better.
It was intended for the howl of the wolf, the sign of his patrol!
CHAPTER XII.
THE AMBUSH.
"I see him, Elmer," whispered Toby.