THE PLOT OF THE BRADY GANG.

The attack of the four men had been engineered with a suddenness that took Matt's breath. The men were not common hoodlums, although they looked the part, but all four of them were men whom Matt recognized.

They were all members of the Brady gang. One was Grove, who had escaped from the South Chicago authorities on the preceding afternoon; another was Harper, who used to drive the Hawk for Brady when the air ship was in his possession; another man was Pete, and the fourth was Whipple.

Matt had seen a picture of Harper in the "rogues' gallery" in the chief's office, and he had had no difficulty in recognizing the rascal at a glance. Harper had been with Grove at the time some blue prints were stolen from Hamilton Jerrold, another inventor of air ships, living in South Chicago. But Harper had been hurt in Jerrold's house and had not got away in the air ship, which the thieves had used to help them commit their robbery.

Pete and Whipple had been with Brady in a rendezvous in Willoughby's swamp, near Lake Station, Indiana. Matt had had some exciting dealings with Grove, Pete, and Whipple, and knew them fairly well.

Ferral, hearing Matt's cry and the rush of feet, had run out of the shed and around the front of the car. As quickly as he could, he leaped to Matt's assistance.

But what could the two boys accomplish against four husky men, all desperately determined to carry out the plot they had formed? Officers of the law were hunting for all of them, and if they did not succeed in their nefarious work, it would not be many hours before they saw the inside of a prison cell.

Matt King never fought better than he did then. He had struck down Whipple, and had thrown himself at Pete.

About the same time, Ferral engaged Grove. Grove had science as well as strength, and was keeping Ferral pretty well occupied.

Whipple, wild with fury, staggered to his feet. He was behind Matt, and Ferral, out of the corner of his eye, saw him preparing to strike.

"Look out, mate!" warned Ferral. "There's a big swab behind you!"

But the warning came too late. Whipple's ham-like fist reached Matt's head, and the young motorist staggered and flung up his arms. Again the enraged Whipple aimed a blow, but Matt dropped to one side, and the fist only grazed his shoulder. Pete, however, had been watching his chance. Throwing himself forward, he dealt a fierce blow with his fist that toppled Matt to the ground.

Harper, meantime, had come up behind Ferral and successfully carried out the same manoeuvre that had been made use of by Whipple. Both boys were brutally knocked off their feet. The moment they were down, Harper fell on Ferral and Pete dropped on Matt, when Whipple turned on Grove.

"Go ter the side o' the shed, Grove," said he, "an' keep yer eyes skinned along the road. If ye see anyone comin', jest let out a yell."

"What's the use of fooling around here any longer?" demanded Grove. "We've got the car, and all we have to do now is to get into her and let the police look up at us."

"Do as I tell ye!" bawled Whipple. "Our work ain't done yet. The ole man told us what ter do with King, an' we're goin' ter do it. He's played hob with Brady's plans, an' the ole man is crazy ter git even. T'other chap, bein' with King, 'll have ter stand fer the same dose."

Grove, muttering to himself, moved off toward the corner of the balloon house. Whipple, hurrying to the car, took out a coil of rope. It was not heavy rope, but fine and pliable.

Cutting off four pieces of the rope, Whipple went to Matt. The young motorist was still dazed from the blows he had received, and it was not difficult for Pete to hold him while Whipple tied his wrists at his back and his feet at the ankles.

Thereupon Whipple passed to Dick and secured him in the same way.

"Anyone in sight yet, Grove?" Whipple asked as he straightened up.

"No," replied Grove.

"Well, keep yer eyes peeled. We're a good ways from bein' through." He turned to Harper and Pete. "Lay holt o' the car, you two," he ordered, "an' pull the Hawk clear o' the shed. Mind ye don't let the gas bag tech the sides o' the door."

"This ain't the first time I've helped with the Hawk," said Harper. "I reckon I know how ter handle her as well as anyone."

Harper and Pete managed to get the air ship out of the shed without injury. This left the opening into the shed clear.

"You two," Whipple went on to Pete and Harper, "pick up that other feller an' kerry him in. I can handle King, all right."

The way Whipple handled Matt was to grab him by the collar and drag him through the door and the length of the shed. At the end of the big room he opened a door and pulled Matt into a small chamber not more than ten feet square by as many high—hardly more than a big box. There was a window in one wall, and two cots at each side.

Halting in front of one of the cots, Whipple picked Matt up in his arms and dumped him upon the narrow bed.

"Put your kid on the other cot," ordered Whipple to Harper and Pete.

Ferral was lifted and placed as the leader of the gang had directed.

Matt had been conscious of every move that was made, although his mind had not been at all clear. By the time he had been placed on the cot, however, his faculties were as keen as ever, in spite of the pain he suffered on account of his rough treatment.

"What are you trying to do, Whipple?" he demanded, turning his head so he could look directly into the face of the leader of the gang.

"What we're tryin' ter do we've as good as done," was the fierce answer. "We're undoin' the thing you done a week er more ago. The perlice are after us, on account o' you, an' we're goin' ter make a getaway in the Hawk."

"The Hawk belongs to me and my friend, on the other cot."

"How d'ye figger that out? I reckoned the Hawk belonged ter Brady."

"Brady is a thief. He stole a lot of stuff, and the Hawk was sold to help pay back the losses of some of the people who were robbed."

"Oh, ho!" laughed Whipple, huskily, "that's the way of it, eh? An' you an' yer chum bought the Hawk?"

"Yes. If you steal her you'll get into trouble—a lot more trouble than you're in already. I guess you've got more now than you can take care of."

"An' it was you as made the trouble fer us!" cried Whipple, with a black scowl, stepping closer to Matt and shaking a fist in his face. "But you're right at the end o' your rope, my buck. Brady never fergits a feller who crosses his plans like you done. Arter we leave here it won't be you that makes the trouble fer us."

"Is Brady in this?" queried Matt, seeking information.

"He's on deck, you bet, an' we're goin' ter pick him up close ter Willoughby's swamp; then we're goin' ter cross the lake an' come down in a place where we'll be safe fer a spell. While we got the Hawk we're safe from the perlice, all right, but we got our operations ter attend to."

"More robbery, I suppose."

"Suppose what ye blam' please, ye'll never be able ter tell anyone what ye're hearin' from me now. What we're goin' ter do to you an' yer chum'll teach others ter let Hector Brady an' his gang alone. If I——"

Just then a shrill whistle came to the ears of those in the little room.

"Listen to that!" exclaimed Pete, in consternation.

"Somebody's comin'!" gasped Harper. "If we don't make a run out of this we'll be nabbed."

Whipple jumped to a gas bracket against one of the rough board walls. It was not an ordinary bracket, but had a wide mouth to which a piece of hose could be attached. This had been used by the police officials to replenish the gas in the silk envelope of the Hawk.

With one jerk of his hand Whipple turned the gas full on.

"Get out!" he called to the two with him.

Pete and Harper tumbled through the door into the shed. Whipple hurried after them but paused a moment on the threshold to give a wild, taunting laugh.

"That's what Brady told us ter do," said he, savagely, "an' we've done it. Git clear o' this, if ye can!"

With that, Whipple slammed the door.

The fate to which the murderous scoundrel had consigned the two boys was a fearful one. Even as the door closed, Matt could smell the odor of gas pouring into the small room and poisoning the air.

"Dick!" he called. "Can you hear me? Do you know what has been going on?"

"Aye, aye, old ship," came from Ferral. "We're bound for Jones', as straight as we can go. We've lost the Hawk, and probably we've lost our lives. Hard luck!"

"Hard luck!" exclaimed Matt. "Why, Dick, it's the hardest luck I ever had come my way. But there's a chance."

"What sort of a chance, mate? I can't see any."

"Grove, one of the gang, was left outside to watch. He was to whistle if anyone came along the road. Didn't you hear him give the warning? If anyone is coming, we can bring them here. Use your lungs, pard! Yell for all you're worth! Our lives may depend on it!"

Fighting frenziedly to free themselves of the ropes about their hands, the boys shouted at the top of their voices for help. They could feel the vitiated air of the room bringing their breath short and hard, and they knew that their voices were getting feebler by degrees. Desperately they continued to call, hoping against hope that they would be heard, and that some one would come to their aid before it was too late.