"They're starting," said Hugh in a low voice. He jumped upon the running board as Bob came along, and climbed into the front seat beside him. "Let's wait here a minute," he whispered.

Down the street in front of the Wernbergs' house they could see men getting into the two automobiles. Presently the whirr of the motors came to their ears and the two cars started. One came towards them and the other went in the opposite direction.

"Which one shall we follow?" whispered Bob.

"Let's follow the one going the other way."

They rolled out of the driveway and started down the street. As they turned into the avenue the first car passed them, a gray roadster bespeaking power and speed in its every detail. Two men were seated in it. Bob and Hugh obtained a fleeting glimpse of them as they flashed by. The tail light of the car they intended to follow showed a dim, red spot far down the street.

"Speed her up a little, Bob," urged Hugh. "We don't want to lose them."

"We can't keep too close to them either," said Bob. "Besides, my thumb and forefinger are pretty sore from that fuse burn and it's hard to grip the wheel."

"Mine are sore too," said Hugh. "Put on gloves."

"I haven't any with me."

"I have; take mine."

Still watching the small red dot ahead of them Bob managed to slip on
Hugh's right-hand glove. It was a great help to him in driving.

"They've turned a corner," exclaimed Hugh suddenly. "Faster, Bob!"

Bob pressed his foot on the accelerator and the car leaped forward as if it were a living thing. A moment later they reached the cross street and turned into it, peering anxiously ahead. The car they were following was still in sight.

"Keep about two hundred yards in back of them," Hugh advised.

"We mustn't lose them."

"No, and we don't want them to get suspicious either."

"They're turning another corner," exclaimed Bob after a few moments.

"Speed it up now that they can't see us."

Bob did so and they came to the corner just in time to see the car they were following pull up at the curb in front of a white stucco house.

"Go ahead, Bob! Go ahead!" urged Hugh. "Don't turn!"

Bob kept straight on. "What street was that?" he asked.

"Elm Street."

"Isn't that where the German on the bridge told Harold he lived?"

"Why so it is," exclaimed Hugh.

"I wonder what number that house is."

"I don't know. Let's see, Howard Seeley lives on Elm Street, just the next block down; his number is eleven hundred and something."

"The German told Harold he lived at twelve eighty-two, and I'll bet you that was the house."

"Whew!" whistled Hugh. "I wonder if it was."

"They probably went to find out why the bridge wasn't blown up to-night," said Bob. "Do you suppose that could be it?"

"Maybe. We could have told them quicker if they'd come to us though," chuckled Hugh. "They'll probably give that fellow the mischief for failing."

"They can't get at him if he's in jail."

"That's so. Suppose we're called as witnesses at his trial? They'll learn that we spoiled their game and our lives won't be worth two cents."

"Well, if those men are plotters we must prove it before the case even comes to trial."

"Do you suppose they have a regular organization to blow up everything around here that they can?" said Hugh. "I should think the secret service would get after them."

"Probably it has; no doubt the names of all those men are listed."

"That is, if they really are plotters."

"Of course. Where are you going!"

They had kept straight on down the road and were now on the outskirts of the city. The houses were fewer and more scattered all the time and presently the boys would be in the open country.

"I don't know," said Bob. "I was just going ahead without thinking."

"We'd better go back, hadn't we? We must be about three miles from home."

"There's a road up ahead here to the right," said Bob. "We can turn down there and go back that way."

When they were about two hundred yards distant from the road in question, an automobile came out of it and turned into the main highway. A moment later it was speeding along in front of Bob and Hugh, the roar of its cutout coming faintly to their ears.

"Bob," exclaimed Hugh excitedly, "that's the gray roadster!"

"What gray roadster?"

"The one we passed in front of your house. It came from the Wernbergs'."

"Shall we follow it?"

"Certainly. It's going like the wind though."

"Well, it can't lose us," said Bob grimly. He advanced the spark, gave the motor more gas and they were soon tearing through the night at fifty miles an hour. Over the crest of a hill in front of them, the gray roadster was outlined for a moment and then disappeared.

Up the grade of the hill Bob drove the big car. When they arrived at the top they peered ahead anxiously for any sign of the machine they followed. Nothing was to be seen of it.

"It's gone," exclaimed Hugh.

"Perhaps not," said Bob. "It can't be very far ahead of us anyway."

They continued down the road at breakneck speed, passing through a clump of woods that lined both sides. Bob forced the motor to its utmost, but no sign of the gray roadster could they discover. Finally he brought the car to a dead stop and turned to Hugh.

"What became of that car?" he demanded. "They weren't far enough ahead of us to have gotten out of sight so quickly."

"They must have turned off into another road," said Hugh. "I don't see what else could have happened."

"But there are no roads into which they could have turned."

"Are you sure?"

"Positively."

Both boys relapsed into silence, completely mystified by the strangeness of the thing. Apparently the roadster had vanished from the face of the earth.

"Wait a minute," cried Bob suddenly. "There is a road back there too."

"I thought there must be."

"Remember those woods back there, just this side of the hill?"

"Yes. That's where we used to go for chestnuts in the fall."

"That's the place. Remember the old house back in there?"

"It's deserted and tumble-down."

"I know it, but there's an old wagon road leading to it."

"Do you think that is where they went?" exclaimed Hugh in surprise.

"Where else could they have gone?"

"I don't know, I'm sure."

"Shall we go back there and see?"

"We can't run the car in there."

"Why not? We can if they can."

"Suppose we should meet them coming out?"

"That's right," exclaimed Bob. "I tell you what we can do though. We'll run back down the road and leave the car and then go to the old house on foot."

"Good scheme," said Hugh readily. "We can hide the car somewhere I suppose."

"Oh, yes. We'll leave it a little way off the road under some trees."

A few moments later Bob had turned the car around and they were speeding back in the direction whence they had come.

"You know where the road is, don't you?" asked Hugh.

"I do," said Bob confidently. "We'll leave the car about a quarter of a mile this side of it and then walk."

"I wonder if they could have gone to that old deserted house," mused Hugh.

"Maybe. I swear I don't see why though."

"We're probably chasing moonbeams," said Hugh.

"Perhaps we are, but we're having a lot of fun anyway."

"Of course we are," exclaimed Hugh, "and I'm for going ahead."

A moment later Bob slowed down the car. A clump of trees appeared alongside the road, and shifting into second speed Bob carefully steered his course toward them. In the shadow of the trees he stopped, shut off the motor, turned off the lights, and stepped out. Hugh got out on the other side.

"Here we are," whispered Bob. "I guess it's all right to leave the car here."

"I should think so," Hugh agreed. "We're about fifteen yards from the road and I don't believe any one would notice it in here."

They started down the road, keeping well to one side, so that they would not show up against the faint white ribbon of the highway as it stretched through the country. After a walk of about five minutes Bob halted.

"There's the road," he whispered, pointing ahead.

"Come on then," urged Hugh. "Carefully now."

It was a weird sensation to be stealing along in the darkness, and the hearts of both boys were pounding. They turned from the main road and started down the narrow wagon track through the woods. It was much darker there and difficult to pick one's path.

A dry twig snapped under Hugh's foot and the boys stopped short, their breath coming fast. The hoot of an owl directly overhead startled them violently and unconsciously they clutched each other's arm. The giant trees loomed black and forbidding in the darkness, and it was easy to imagine all kinds of things lurking behind to spring out at them.

"I don't like this," whispered Hugh. "How far is it from here?"

"Just a short distance. I don't like it either."

Presently Bob tugged at Hugh's sleeve. "There's a light," he said softly.

A faint glimmer appeared through the darkness ahead. Presently the boys were able to see that it came from a lantern held by some man standing in the open doorway of the old house. A moment later four others appeared from within and came out to the tumble-down porch. Bob and Hugh looked on with bated breath. What could it all mean?