“Going to make a bonfire of me, eh?” Quest remarked.

“You can sneer, my fine friend,” the man growled.  “You’ve had a good many comfortable years of wearing fine clothes and smoking twenty-five-cent cigars, swaggering about and hunting poor guys that never did you any harm.  This is where we are going to get a bit of our own back.  See here!  We are locking this door—­like that.  It’s a lonely bit of the line.  The man in the tower never takes his eyes off the signals and there ain’t a soul in sight.  Me and my mate are off to the section house.  Two minutes will see us there and back.  We’re going to bring a can of oil and an armful of waste.  Can you tell what for, eh?  We’re going to burn the place to a cinder in less than three minutes, and if you’re alive when the walls come down, we’ll try a little rifle practise at you, see?”

“Sounds remarkably unpleasant,” Quest admitted.  “You’d better hurry or the boss will be back.”

Gallagher finally slammed the door.  Quest heard the heavy footsteps of the two men as they turned towards the section house.  He drew a little case from his coat pocket.

“Just as well, perhaps,” he said softly to himself, “that I perfected this instrument.  It’s rather close quarters here.”

He opened what seemed to be a little mahogany box, looked at the ball of black substance inside, closed it up, placed it against the far wall, untwisted the coil, stood back near the door and pressed the button.  The result was extraordinary.  The whole of the far wall was blown out and for some distance in front the ground was furrowed up by the explosion.  Quest replaced the instrument in his pocket, sprang through the opening and ran for the tower house.  Behind him, on its way to New York, he could see a freight train coming along.  He could hear, too, Red Gallagher’s roar of anger.  It was less than fifty yards, yet already, as he reached the shelter of the tower, the thunder of the freight sounded in Quest’s ears.  He glanced around.  Red Gallagher and his mate were racing almost beside it towards him.  He rushed up the narrow stairs into the signal room, tearing open his coat to show his official badge.

“Stop the freight,” he shouted to the operator.  “Quick!  I’m Sanford Quest, detective—­special powers from the chief commissioner.”

The man moved to the signal.  Another voice thundered in his ears.  He turned swiftly around.  The Irishman’s red head had appeared at the top of the staircase.

“Drop that signal and I’ll blow you into bits!” he shouted.

The operator hesitated, dazed.

“Walk towards me,” Gallagher shouted.  “Look here, you guy, this’ll show you whether I’m in earnest or not!”

A bullet passed within a few inches of the operator’s head.  He came slowly across the room.  Below they could hear the roar of the freight.

“This ain’t your job,” the Irishman continued savagely.  “We want the cop, and we’re going to have him.”