“And I reckon we’ll take along one of the gang as a matter of precaution,” said Labar. “There’s every modern convenience in this tunnel, including steel doors which may be awkward to open.”

A man was selected from the prisoners and the little band of armed police officers started on their tour of exploration. Bill Malone elected to take the prisoner in his own charge and poking him with the muzzle of a pistol gave expression to prophesies of sudden and horrid calamity in the event of any monkey business.

As they arrived at the first barrier Labar swung his torch and a sharp oath slipped from between his lips. That door he was confident had been left open. Now it was closed.

The white-faced prisoner under the persuasion of a dig in the ribs from Malone’s pistol point was called upon to open it. But it resisted all his efforts.

“No good, sir,” he said. “It’s locked on the inside.”

“Here’s a nice game,” observed Malone.