Direct as an arrow the man glided forward. Now he was ten feet from the steel door, and paused to listen. Two steps more, and a second pause. And now his hand was nearing the shining metal knob that controlled the combination lock of the vault. Again he appeared to listen.
At that second, Johnny’s eyes fairly popped out of his head—a strange thing was taking place. The knob which had been white in the semi-darkness, had turned a dull red!
“The mysterious fire!” he whispered, almost aloud.
The next instant there came a strange hissing cry of pain. The person crouching there, without noting the red glow, had grasped the knob.
For a second he appeared to study the knob; then, without as much as looking backward, he turned and darted away.
Frozen in his tracks, Johnny stood staring at the knob until the red glow had faded out and the knob shone white once more.
A long time he stood there, his mind rife with wild wonderings. What was this white fire? Whence its origin? Johnny was not superstitious; he felt that some human being was back of it all. But that human being, was he friend or foe? If friend, then he had frightened the enemy away! If enemy, then he had known of Johnny’s presence and had used this means to warn his confederate.
Presently, when his mind was again composed, he thought of the lunch-box and with trembling fingers reached down to lift it from the floor.
What would it disclose? How would its contents affect the mystery he was trying to solve?
Johnny drew a deep breath, and grinned happily.