And now to return to Bob and Joe, as, panting with their exertions and followed by their comrades, they rushed toward the old factory from which they hoped to reach the rear of Mr. Layton’s store.

The place had formerly been used by a chemical concern with which Mr. Layton was connected in an advisory capacity. He was skilled in his profession and his services had been highly appreciated. An amalgamation of several similar concerns had now been effected, and for purposes of economy the headquarters of the company had been removed to another city and the old factory had been abandoned.

While it had been in operation it had been connected with the rear of Mr. Layton’s store by an underground tunnel that was just large enough to permit easy access from one place to the other. A large door closed it at the factory end, while at the rear of the store a flight of steps led up to a large, square trapdoor set in the floor.

Bob’s mind was in a tumult of emotions as he ran along. It was a long time since he had been in the factory, and in the confusion of his thoughts he could not remember whether the great door was locked or not. And even if he succeeded in gaining access there, the possibility remained that the trapdoor at the other end might prove to be bolted. In either case, it would be impossible to get into the store until it was too late to be of any use. And at this very moment his father might be gasping out his life in those terrible fumes!

He reached the factory, flung himself through the open outer door and made for the door leading into the passageway. He pulled frantically at the knob, but it resisted his efforts. Was it locked, after all? The answer was supplied the next moment when Joe added his strength to Bob’s, and yielding to their united efforts the heavy door, groaning and creaking on its rusted hinges, swung outward. Jimmy and Herb had been outdistanced and were nowhere to be seen.

With an inward prayer of gratitude Bob plunged into the dusty passage that had been unused for years. Fortunately it ran in a straight line, and although he had no light he had little difficulty in finding his way, despite the fact that he abraded his hands and shins against the sides, owing to the rate at which he was going. But in his excitement the youth did not even feel the bruises.

In a moment he had reached the foot of the steps, bounded up them and was pushing with all his might at the trapdoor at the head. It yielded under his efforts enough to show that it was not bolted. For a moment though, it seemed as though it might as well have been, for some heavy object or objects lying on it defied his strength. By this time Joe was at his side, and together they strained at the door, while the veins stood out in ridges along their arms and shoulders. Had they not been strung up to such a pitch, they could never have succeeded, but sheer desperation gave them strength far beyond the normal, and gradually they forced the trap upward and rolled over to one side what had been holding it down.

In a twinkling both the boys were up in the store. The fumes had thinned out somewhat, but were still thick enough to make them gasp and choke. Whatever they had to do must be done quickly.

CHAPTER III
QUICK WORK

The room into which the boys had leaped was a small laboratory fitted up in the rear of the store. As Bob’s eyes ranged about, they fell on two bodies lying at the side of the trapdoor. These were what had been holding the trapdoor down. A glance sufficed to show Bob that one was the body of his father and the other that of Thompson, one of the clerks of the store.