Johnny’s journeys on foot that night were long and varied. In the spur leading to the museum there were no lights. He was obliged to depend upon his electric torch. This cast weird shadows. Every now and then he fancied he detected a crouching figure ahead. Each time as he advanced it proved to be only a pile of supplies in a niche in the wall, or a padlocked tool box.  
“Probably no one anywhere,” he grumbled to himself. “Great waste of time.”
 
He was wrong. There was someone.
 
Coming at last to the end of the museum spur, he examined the elevator carefully. He did not attempt to ascend to the museum as Curlie had done. Instead, he turned and retraced his steps.
 
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On the return journey he did not exercise the caution resorted to on coming to the museum. It did not seem necessary. He was looking for someone who might be in hiding. The person had not been found. It was natural to suppose that on his return he would find no one.
 
In this world one must learn that nothing may be taken for granted. With his flashlight pointed at his toes, Johnny had not gone a hundred paces on his return journey before, to his vast surprise, a figure sprang up from the darkness directly before him and went sprinting down the track.
 
So astonished was he that for a full ten seconds he stood motionless. This gave the fugitive a start.
 
“Must have been following me,” Johnny’s mind registered at last. “Wonder why?”
 
The next thought was: “He may be my man!” This startled him into action. Throwing his light far ahead, he saw the man plainly, even his face, for just then he looked back.
 
It was a wild sort of face, with a stubby beard, unkempt hair and no hat.
 
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“That,” he thought, “is not my man. And yet—a day and a night in a tunnel. Who knows?”
 
At that he sprang away after the fugitive.
 
From the museum to the main line of tunnel is three eighths of a mile. The man was not a good runner. Johnny was. He gained. Foot by foot, yard by yard, rod by rod, he shortened the distance between them. Now he was five hundred feet behind, now three hundred, now two hundred, now—
 
But suddenly, as they neared the main line, the fugitive stopped. He appeared to place something in the center of the track. Then at redoubled speed he raced on.
 
At that moment Johnny seemed to hear a voice cry:
 
“Stop! Go back! Back!”
 
Was it a human voice? Was it a superhuman voice, or was it no voice at all? In the light of that which followed Johnny will always believe it to have been a human voice.
 
At any rate, he obeyed. He stopped.
 
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It was well that he did. Ten seconds had not passed when the whole world appeared to have been blown into fragments.
 
Johnny was thrown twenty feet, to go crashing against the wall. He rolled over once, then lay quite still.
 
For a short time the place remained in utter silence. Then there was a sound; but Johnny did not hear it. It was a most ominous sound. It increased in volume as the seconds passed. It was the sound of rushing water. Above the tunnel, between it and the surface of the street run the great water mains that quench the city’s thirst and protect it from devastating fires. The explosion had torn away the thin tunnel wall and had broken one of these water mains.
 
What would follow was a thing prearranged and quite automatic. Great iron doors at the end of the museum spur would close. This would confine the flood to the spur. The main tunnel would be safe from flood. In time the motor would be shut off and the main mended. Not, however, until the museum spur had been filled with water, perhaps for hours.
 
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In the meantime Johnny lay where he had fallen. He............