"It should be right here," he whispered.
Haggerty pointed in silence. In the starlight, a large rock loomed up a few yards away. With an exclamation of satisfaction, Carnes led the way to it.
"Dig on the south side," he whispered, "and hurry! The damned thing is due to go off in less than twenty minutes. Unless we can find and cut the wire before then, the doctor is a gone gosling."
The two detectives drew intrenching shovels from their pockets and dug feverishly. For five minutes they labored. Dillon gave an exclamation.
"Here it is, Chief!" he said.
Carnes bent down and ventured a short flash from a carefully guarded light. The detective's shovel had unearthed a powerful cable running through the earth.
"Get something to cut on!" cried Carnes.
Haggerty lifted a rock which they had unearthed and thrown to one side. Carnes raised the cable and laid it on the rock.
"Now for your ax, Dillon!" he exclaimed.
He turned on his flashlight. Dillon raised a hand-ax and took careful aim. Sparks flew as the ax fell on the rock, severing the cable cleanly. Carnes rose to his feet.