Ribiera's face was a gray mask of terror when they reached the door. A long, low car with two men on the chauffeur's seat was waiting.

"Only one man up front, Ribiera," said Bell dryly. "No ostentation, please. Now, I hope your servants haven't summoned the police, because they might want to stop me from marching you out there with a gun in the small of your back. And that would be deplorable, Ribiera. Quite deplorable."

With a glance, he ordered Paula into the tonneau. He followed her, driving Ribiera before him. There seemed to be none about but the stricken, terrified servant who had opened the door for their exit.

"My friend," Bell told the major-domo grimly, "I'll give you a bit of comfort. I'm not going to try to take the Senhor Ribiera away with me.

Once I'm on board the yacht that waits for me, I'll release him so he can keep you poor devils sane until my Government has found a way to beat this devilish poison of his. Then I'll come back and kill him.

Now you can tell the chauffeur to drive us to the Biera Mar."

He settled back in his seat. There were beads of perspiration on his forehead, but he could not wipe them off. He held the two revolvers against Ribiera's flabby body.

The car turned the corner, and he added dryly:

"Your servants, Ribiera, will warn your more prominent slaves of my intention of going on board a yacht. Preparations will be made to stop every pleasure boat and search it for me. So ... tell your chauffeur to swing about and make for the flying field. And tell him to drive carefully, by the way. I've still got these guns on a very fine adjustment of the trigger-pressure."

Ribiera croaked the order. Bell was exactly savage enough to kill him if he did not escape.

For twenty minutes the car sped through the residential districts of Rio. The sun was high in the air, but clouds were banking up above the Pao d'a.s.sucar--the Sugarloaf--and it looked as if there might be one of the sudden summer thunderstorms that sometimes sweep Rio.

Then the clear road to the flying field. Rio has the largest metropolitan district in the world, but a great deal of it is piled on end, and Rio itself built on most of the rest. The flying field is necessarily some miles from even the residential districts, for the sake of a level plain of sufficient area.

The car shot ahead through practically untouched jungle, interspersed with tiny clearings in which were patchwork houses that might have been a thousand miles in the interior instead of so near the center of all civilization in Brazil. Up smooth gradients. Around beautifully engineered curves.

Bell put aside one revolver long enough to search Ribiera carefully.

He found a pearl-handled automatic, and handed it to Paula.

"Worth having," he said cheerfully. "I wonder if you'd mind searching the chauffeur: with that gun at his head I think he'd be peaceful. You needn't have him stop."

Paula stood up, smiling a little.

"I did not think I lacked courage, Senhor," she observed, "but you have taught me more."

"_Nil desperandum_," said Bell lightly. He relaxed deliberately.

Matters would be tense at the flying field, and he would need to be wholly calm. There was little danger of an attempt at rescue here, and the necessity of being ready to shoot Ribiera at any instant was no longer a matter of split seconds.

He watched, while, bent over the back of the front seat, she extracted two squat weapons from the chauffeur's pockets.

"Quite an a.r.s.enal," said Bell as he pocketed them. He turned pleasantly to Ribiera. "Now, Ribiera, you understand just what I want.

That big amphibian plane of yours is fairly fast, and once when I was merely your guest you a.s.sured me that it was always kept fueled and even provisioned for a long flight. When we reach the flying field I want it rolled out and warmed up, over at the other end of the field from the flying line. We'll go over to it in the car.

"And I've thought of something. It worried me, before, because sometimes if a man's shot he merely relaxes all over. So while we're at the flying field I'm going to be holding back the triggers of these guns with my thumbs. I don't have to pull the trigger at all--just let go and they'll go off. It isn't so fine an adjustment as I had just now, but it's safer for you as long as you behave. And you might urge your chauffeur to be cautious. I do hope, Ribiera, that you won't look as if you were frightened. If there's any hitch, and delay for letting some fuel out of the tanks or messing up the motors, I'll be very sorry for you."

The car swooped out into bright sunshine. The flying field lay below, already in the shadow of the banking clouds above. Hangars lay stretched out across the level s.p.a.ce.

Through the gates. Ribiera licked his lips. Bell jammed the revolver muzzles closer against his sides. The chauffeur halted the car. Paula spoke softly to him. He stiffened. Bell found it possible to smile faintly.

Ribiera gave orders. There was a moment's pause--the revolver muzzles went deeper into his side--and he snarled a repet.i.tion. The official cringed and moved swiftly.

"You have chosen your slaves well, Ribiera," said Bell coolly. "They seem to occupy all strategic positions. We'll ride across."

The gears clashed. The car swerved forward and went deliberately across the wide clear s.p.a.ce that was the flying field. It halted near the farther side. In minutes the door of a hangar swung wide. There was the sputtering of a not-yet-warmed-up motor. The big plane came slowly out, its motors coughing now and then. It swung clumsily across the field, turned in a wide circle, and stopped some forty or fifty feet from the car.

"Send the mechanic back, on foot," said Bell softly.

Again Ribiera found it expedient to snarl. And Bell added, gently, while the throttled-down motors of the big amphibian boomed on:

"Now get out of the car."

Tiny figures began to gaze curiously at them from the row of hangars.

The mechanic, starting back on foot, the four people getting out of the car, the big plane waiting....

With his revolver ready and aimed at Ribiera's bulk, Bell reached in the front of the car and turned off the switch. The motor died abruptly. He put the key in his pocket.

"Just to get a minute or two extra start," he said dryly. "Climb up in the plane, Paula."

She obeyed, and turned at the top.

"I will cover them until you are up," she said quietly.

Bell laughed, now. A genuine laugh, for the first time in many days.

"We do work together!" he said cheerfully.

But he backed up the ladder. There was a stirring over by the hangars.

The mechanic who had taxied the plane to this spot was a dwindling speck, no more than a third of the way across the field. But even from the distant hangars it could be seen that something was wrong.

"Close the door, Paula," said Bell. He had seated himself at the controls, and scanned the instruments closely.

This machine was heavy and large and ma.s.sive. The boat-body between the retractable wheels added weight to the structure, and when Bell gave it the gun it seemed to pick up speed with an irritating slowness, and to roll and lurch very heavily when it did begin to approach flying speed. The run was long before the tail came up. It was longer before the joltings lessened and the plane began to rise slowly, with the solid steadiness that only a large and heavily loaded plane can compa.s.s.

Up, and up.... Bell was three hundred feet high when he crossed the hangars and saw tiny faces staring up at him. Some of the small figures were pointing across the field. The big plane circled widely, gaining alt.i.tude, and Bell gazed down. Ribiera was gesticulating wildly, pointing upward to the soaring thing, shaking his fist at it, and making imperious, frantic motions of command.

Bell took one quick glance all about the horizon. Toward the sea the sun shone down brilliantly upon the city. Inland a broad white wall of advancing rain moved toward the coastline. And Bell smiled frostily, and flung the big ship into a dive and swooped down upon Ribiera as a hawk might swoop at a chicken.

Ribiera saw the monster thing bearing down savagely, its motors bellowing, its nose pointed directly at him. And there is absolutely nothing more terrifying upon the earth than to see a plane diving upon you with deadly intent. A panic that throws back to non-human ancestors seizes upon a man. He feels the paralysis of those ancient anthropoids who were preyed upon by dying races of winged monsters in the past. That racial, atavistic terror seizes upon him.