But, with the crack of the revolver the great crowd became a wild, howling mob.  Shrieks, screams and cries of anger filled the air, and as a single man the crowd swooped upon the spot where a tall man with a smoking revolver in his hand was attempting to make his escape.

Chester, who had been prepared for the shot, sprang forward upon the instant, with Jean but a step behind him.  Through the crowd they were forced to fight their way, but eventually they came to the edge of it, only to find that Duval, for such they were sure the would-be assassin was, had fought his way out and fled.

But, as the Apache chief ran, the crowd dashed after him.  Chester now had his school days to thank for the fact that he was more fleet of foot than the others of the crowd.  He passed them rapidly, as he ran after the flying figure of Duval, now at least 200 yards ahead of him down the street.

The lad raised his revolver as he ran and fired.  But Duval did not halt.  Chester had missed.

With the howling pack at his heels, and Chester gradually closing up the gap between them, Duval exerted himself to the utmost.  Suddenly he turned into a narrow alley, where he halted.  Chester, who was nearer than any of the others, dashed into the alley without slackening his speed, and, as he did so, Duval struck him a heavy blow in the face with the butt of his revolver.

Immediately he turned and dashed forward again.

Chester was not knocked unconscious by the force of the blow, but he reeled and fell to the ground.  He was up in a moment, however, and with blood streaming from an ugly gash in his head, dashed after the fugitive once more.

Gradually Duval and his pursuer outdistanced the rest of the crowd.  Chester was near enough not to be thrown off the track, as Duval rounded corner after corner; and, try as he would to shake off his pursuer, Duval was unable to do so.

At the next corner Duval darted into a little store, and out the other side, upsetting a group of men as he did so.  Chester dashed in after him.

But here he encountered an obstacle.  The group of men upset by Duval rose to their feet, very angry.  At the sight of a second running man, not realizing the seriousness of the chase, they lined up and stopped the lad’s progress.

Realizing it was no time for talk, Chester struck out right and left, and men dropped.  But the rest closed in, and Chester went down.  A heavy wrench was raised over his head and would have fallen on it.

But a newcomer caught the upraised arm.  Chester looked up.  It was Hal.

CHAPTER XXVII.

HAL IN PERIL.

Hal was unable to tell just what caused the great crash as, after releasing his hold on the window in the cellar of the house to which he had followed Duval he went down into space.  His feet struck a projection of some kind, and the crash followed.