"It might not have been a shot!" suggested Will.
As the boy spoke he bent over and pointed to three stones lying on the floor of the gangway.
"There!" he said. "The boys have left a record. They not only point out the trail, but warn, us that there is danger in following it!"
Chapter XVIII
TWO HOLD-UP MEN
"That's Boy Scout talk all right!" exclaimed Elmer.
"Yes, the three stones, piled one on top of the other, mean that there is danger in following the trail. I don't understand exactly what kind of danger can be threatening us, and so the only thing we can do is to go on and find out," Will said with a glance backward.
The other boys now came up and a short consultation was held. It was decided to leave Sandy and Dick at the point where the explosion had taken place, while Will, Elmer and Jimmie followed on down the gangway.
"Now whatever you do," warned Will as the two boys were left behind, "don't leave this gangway for a minute. If Ventner isn't out of the mine now, we don't want him to get out. He may have the money or he may not. That is one of the things no fellow can find out at this time, but whether he has or not, we want him to give an account of himself before he leaves the Labyrinth. He's got several important questions to answer."