"Then who is the chief? He's here somewhere and Slater sure didn't intend to take orders from Harror."

"He must be on the train," Blake answered.

"Now you're crazy," O'Toole answered savagely. "The people on Mono 6 have been locked up for hours. If the leader of the Silver Masks was among them he'd have taken charge hours ago."

"Unless," Blake said thoughtfully, "he didn't want any of us to _know_ he was the leader."

O'Toole pulled the mask down over his eyes.

"Let's get out of here," he said. "You've got something up your sleeve and I'll play the cards the way you want them."

"One more thing," Blake told him. "These men had to have a track to get Mono 6 into this cave. When it goes out again we'll be on the same track, but it will end in a canyon or deep lake."

"Go on."

"Well! We've got to get started on that trip. After we are out you and I will have to take our chances of stopping the mono."

"And I thought Grudge Harror was a tough baby," O'Toole grinned.

"It isn't a matter of being tough," Blake said. "Can you handle the engine room alone?"

"Handled it for years," O'Toole said coolly. "But I'd like to know where that track ends."

"You will." Blake went toward the door. He gripped O'Toole's shoulder.

"You're a good Irishman, O'Toole. Now go out of here and straight to the cab. I don't think they'll dare send one of the other men. If the controls are tied into place, leave them alone. When I signal, set all motors going full speed. Sit tight and keep her flying."

"And the end of the track?" O'Toole asked. "If I don't get shot in the back before I'm half way across the cave, how do I know when to stop?"

Blake chuckled dryly.

"Perhaps you won't," he admitted. "But I'll be in the rear lounge with every male pa.s.senger within my sight. One of them is bound to break down when he knows he's at the end of the trail."

"So?"

"I'll jerk the emergency cord," Blake said. "Set your brakes the minute you hear it. O'Toole, it's a long chance but we've got to take it."

"One more thing," O'Toole asked. "Blake, who in h.e.l.l is the leader of the Silver Masks?"

Blake hesitated, his face darkening. He opened the door and pushed O'Toole out gently.

"If I'm not mistaken," he whispered evenly, "Walter Ferrell knows more about this than he's telling."

The gang of Silver Masks were gathered around the front end of Mono 6 as Holly O'Toole and Jeff Blake emerged from Harror's office. They walked swiftly toward the cab, and Slater who had evidently been waiting, stepped from the crowd and came toward them.

"How about it?" He addressed Holly O'Toole, as O'Toole seemed to be leading Blake. "Everything has been stripped from the baggage cars.

She's ready for her trip into the lake."

"Okay!" O'Toole mumbled. He turned to Blake. "Take two men and get all the pa.s.sengers into the lounge car."

Blake's heart was pounding wildly. If O'Toole slipped now, they'd all pay for it. He turned toward the crowd of waiting masked men.

"Two of you guys step out," he ordered. "Open the doors and herd those cattle into the last car back."

They obeyed him instantly. In five minutes every man and woman in the flyer were crowded into the car with Walter Ferrell and Dauna. O'Toole hesitated, started to climb into the cab of Mono 6, and Slater stopped him.

Standing a few feet away, Blake heard them mumble something. O'Toole pointed to Blake.

"I'll see that she gets clear of the cave," he said in a loud voice.

"The boss wants him to be in the car until it's started and on the way down."

Slater hesitated, nodded and turned away. O'Toole winked and Blake grinned back at him. The Irishman had done a swell job. This was one night when his blarney had been a blessing.

When Jeff Blake went into the lounge car, he drew his electro gun. The car was full of frightened women and angry men. He was afraid they might turn on him in the Silver Mask, and spoil his plans. Slater had followed him to the door.

"Don't stick too long," the man cautioned him. "You'll be doing a hundred miles an hour before you hit the head end of the valley. The boss is going to jump when he leaves the cave."

The boss? Then O'Toole really had done a good job. Automatically Blake looked toward Walter Ferrell, and noticed that he was of the same build and size as O'Toole. Slater couldn't see the occupants of the car, but he guessed who Blake was staring at.

"Take good care of Ferrell," Slater said in a dry whisper. "He's worth a lot of money to us."

Blake grinned.

"_Don't worry_," he said. "_I'll take good care of him._"

Mono 6 started to glide smoothly back out of the cave. Somewhere out of sight behind the flyer, a huge door opened in the side of the mountain and screeched its way into the concealed slit above. The train gathered speed swiftly, and the moon suddenly appeared from nowhere. Blake waited, made sure there were no guards remaining on board. Then he ran swiftly toward the group around Ferrell. He ripped the mask off as he moved, and Dauna, her eyes glued to his face, gasped in happy surprise.

"Jeff," she ran toward him, "Oh! Jeff, I'm so glad."

He pressed his lips to hers quickly, turned away without a word and faced Walter Ferrell. Ferrell's face was expressionless, frightened.

"_Jeff Blake_," he said. "How did you make it?"

"There isn't time to talk now," Blake answered quickly. "O'Toole and I overcame Harror. We managed to get them to start Mono 6 out of the cave.

O'Toole is in the cab now. In a few minutes we'll be free. Before they wake up to the trick we played on them we'll be five hundred miles away."

Ferrell's face relaxed. Although Blake watched him closely, the man showed no sign of alarm.

"Good work, boy." His hand gripped Blake's shoulder. "I don't know how you did it, but there'll be a big reward for you when we reach South Station."

Blake sat down opposite him. His eyes never left Ferrell's face. Yet, Ferrell held himself remarkably in reserve.

"I did it more for Dauna than anyone else," Blake admitted slowly. "We wouldn't have anything happen to her would we?"