Long Tom's device indicated answers to all four of these questions to be the truth.

"Do you have criminal records?" Doc asked.

"No."

They were both liars there, however, according to the detector.

"We'll take them downstairs," Doc said, "and take a cab to headquarters."

THE trip uptown was uneventful, and so was the ride up in the private elevator to the eighty-sixth floor; but when they approached the door, they saw an envelope that had been stuck to the panel with a bit of chewing gum.

"Now what's this?" Monk grumbled, and opened the envelope. Printed lettering on the one sheet inside said: HOW DOES THIS STRIKE YOU FOR A TRADE? YOUR FRIEND RENNY IN EXCHANGE.

FOR MARK AND RUTH COLORADO.

WE TRIED TO BORROW YOUR CAR. REMEMBER?.

"Spad Ames wants the two Colorados mighty bad," Monk muttered. "I wonder why?"

No one told him why. Doc Savage went into the laboratory, returned with a hypodermic needle, and used the contents to put both of their captives to sleep.

"Bring them along," the bronze man said.

They used another car from the private garage, this machine a dark sedan that had size, power and the impregnability of a battleship turret without being conspicuous, and drove to a small private hospital on the West Side, where they unloaded the two sleeping prisoners.

The hospital, although no one but the managing director knew the fact, was maintained by Doc Savage as a completely charitable inst.i.tution for the nearby slum sections. The two captives would be held there until called for.

"These will go to college," Doc told the hospital director, indicating the two senseless ex-members of Spad Ames' gang.

These cryptic instructions would result in an ambulance calling for the pair before many hours had pa.s.sed, and taking them to a unique inst.i.tution for curing criminals which Doc Savage maintained in a remote, mountainous and almost uninhabited section of up-state New York. At this inst.i.tution, surgeons trained by Doc Savage would perform delicate brain operations which would wipe out all memory of the past. The pair would receive training in some trade, would be taught to hate crime and criminals, afterwhich they would be released to become citizens of some value. No crook-once having matriculated in this unusual "college"-ever returned to crime.

Existence of this "college" was kept from the public for various reasons, one being that the place was a little unorthodox; and this method of curing criminals, while it was one that Doc felt would eventually be used widely, was somewhat too fantastic for public acceptance.

"Now," Monk said grimly, "if we just had a way of locating Renny."

"We have," Doc said.

"Huh?"

The bronze man switched on the radio which, instead of being located under the dash, was clamped against the car top, just back of the windshield. It was a compact set, both transmitter and receiver, as well as convertible into a direction finder. Doc made the conversion by throwing switches, and stopping the car and fitting a small collapsible loop aerial into the weatherproof socket on top.

Monk suddenly remembered the perfectly obvious fact that all of Doc Savage's private machines were equipped with two-way radio apparatus.

"Doc!" he exploded. "In that taxicab Spad Ames took from us-you didn't leave the radio, on, by any chance?"

"I left the transmitter switched on," Doc admitted.

Monk emitted a pleased whoop. "Then it's probably still on, because the transmitter don't make any noise, so they wouldn't notice it."

Long Tom said: "Then we can locate the car simply by taking bearings on the transmitter carrier wave with our finder."

Doc nodded; he was busy with the direction-finder.

Chapter IX. TRAILS WEST.

BY three o'clock in the morning, the fog had turned to thin rain that poured down in long strings and made sheets on the windshield wherever it was not knocked away by the wipers. The big car ran silently, the tires making, as they threw water, more noise than the engine of the machine.

The road was rough-it was well north of the city-and the car bucked enough to keep them hanging to the support straps. Monk, Ham and Long Tom would have been uneasy had any one of them been driving at such speed, but their confidence in Doc's tooling of the machine was complete, so they were relaxing as much as they could.

"Naturally, they would go north," Ham said grimly. "That way, they would not have to use bridges, ferries or tunnels over the East River or Hudson that are easily watched."

Long Tom emitted a sharp noise.

"Hep!" said Long Tom. "We've pa.s.sed it up."

He had been manipulating the direction finder steadily; the loop had swung around sharply, following the signal, until it was at right angles to the car."We just pa.s.sed a side road," Ham said.

Doc continued driving. "We will go on a bit, in case they should be watching the road," he explained.

Half a mile beyond, after they had rounded a curve, the bronze man wheeled their machine off the rough blacktop pavement and stopped.

Ham opened the door, grumbled: "Have we got to get out and swim in this?"

"Too bad about them clothes of yours," Monk said.

Doc took the radio along. It could be made portable by loosening thumb screws, an emergency set of batteries being self-contained.

The rain poured down, brush beat their faces and their feet sank in a lot of wet leaves. Trees thickened, and the branches lacked a canopy that shut out any light there might have been.

There was a thump, and Monk croaked, "Oaf! I mashed my face flat against a tree!"

"Probably improved it," Ham said cheerfully.

Doc Savage suggested: "Use the scanners."

The "scanner" was a device perfected by Doc Savage, and so complicated that only Monk and the missing Renny had any accurate idea of how it functioned. There was a projector that put out "black"

light, or light with a wavelength near the infrared spectrum, and which was called "black" because it was invisible to the unaided human eye. The goggles which enabled the wearer to see by "black" light had lenses resembling condensed-milk cans, and functioned through the medium of rotating screens coated with a substance which briefly retained a "picture" formed by the infrared light.

They donned the scanner. Seen through the devices, their surroundings were a vague, unreal panorama of bone-colored objects and intensely black shadows. But it was literally seeing in the dark; no one unequipped with the scanners would realize there was any light at all. Doc Savage had used the devices before; they gave a tremendous advantage in any fight in darkness.

They made good time for twenty minutes through the rain.

"This looks like it," Monk said, and they had been walking in such an unreal world, as seen through the scanner goggles, that his voice caused all the others to jump.

THE cabin was not constructed of genuine logs, but of sawed imitations nailed on over a framework of ordinary lumber, although in spite of that it would be an attractive place seen in better weather. There was a wide porch, and on this stood two men with shotguns.

The taxicab containing the radio they had trailed stood nearby.

"We could walk up," Monk whispered, "and cold-crack them two lookouts as easy as falling off a log."

"Careful does it," Doc warned. "We have had enough fighting and charging around for one night. It is about time we made some progress."

No trace of light whatever came from the cabin itself.

They had been standing there some moments when two automobiles, both sedans, came laboring up in the mud and the rain. The cabin door opened and spilled a great blade of light into the night-it wasinstantly evident that they had the cabin windows blanketed-and Spad Ames came out.

Locatella alighted from one of the cars.

"Here's the rest of your men, Spad," he called. "Sixteen of them. Sixteen was the best I could do."

Spad Ames swore admiringly. "How you got sixteen together so quick beats me."

"Oh, I have my contacts," Locatella said smugly. "In fact, I keep quite an organization together for little jobs which bob up now and then."

The men dashed into the cabin, and Spad Ames and Locatella switched off the car lights, so that the resulting darkness and the noise of the drizzling rain made it perfectly safe for Doc Savage to approach close enough to overhear.

Spad Ames asked: "What about the machine guns, the bombs and the gas?"

"Already on its way west," Locatella said. "The pilot was willing to take off in this weather, which gives you some idea of the kind of a pilot he is."

"You sent the stuff ahead by plane?" Spad said admiringly.

"Yes."

"And that fellow Renny Renwick? We don't want him dead yet."

"On the plane with our weapons. I figured we should get him out of Doc Savage's reach until we made a trade-or got hold of the Colorados ourselves, after which we can drop him out of a plane or something."

Spad Ames nodded, asked: "What about ourselves? Where do we get planes?"

"We've got them," Locatella said, and laughed. "This cabin is one of my places. It's not held in my name, you understand. It's-well, I've got two or three of them scattered around in case of emergencies."

Spad Ames said admiringly: "You don't overlook many bets, do you? But what about planes for ourselves?"

"Come on," Locatella requested.

"Hey, in this rain-"

"It's not far."

Spad Ames and Locatella moved away, entering a narrow path walled thickly with shrubbery and overhung by leaf.a.ge. They dashed the beams of flashlights ahead of them as they walked, so Doc Savage used care, not only to keep out of range of the lights, but to keep from being silhouetted between the lights and one of the guards on the cabin porch.

Suddenly they came out on the edge of a level meadow across which wind drove the rain in slanting, twisting wisps.

The hangar on the meadow edge was large without being conspicuous. Locatella worked briefly with a key and the padlock on the hangar door, then rolled the door back."Nice, eh?" he asked.

The two lean silver planes inside appeared, at first glance, smaller than they actually were, being streamlined to an extreme degree. They were dual-motored, the engine being the water-cooled type which lends itself to more effective streamlining.

"My personal ships," Locatella explained. "Two honeys-and they ought to be. They cost enough. I've only had them about three months."

"What about machine-gun mounts?"

"Already drilled. All you have to do is clamp the guns in. I have the guns, too, incidentally."

"Then we can take off for the west as soon as we get Mark and Ruth Colorado."

"Nothing to prevent."

Spad Ames rubbed his hands together. "This is swell. Perfect. When I came to the well-dressed Mr.

Locatella, I sure didn't make a mistake, did I?"

Locatella gave his companion in crime a big confidential smile. "I'm glad you're satisfied, Spad, old pal."

Locatella clapped Spad on the shoulder. "You know by now that you can trust me. So suppose you be a good fellow and tell me what you're after. Yes, indeed, tell me. What about the black arrowheads, and what about this going into the mists? It sounds very interesting."

"The h.e.l.l with you, my genial friend!" Spad Ames said. "The h.e.l.l with you!"

AFTER Spad Ames and Locatella-a drought of words had fallen between them-had gone back to the cabin, Doc Savage joined his men, who had been waiting in the brush. Long Tom was holding the two-way car radio in his arms, and Monk was carrying the loop aerial for the device.

"You heard what they said?" Monk asked grimly. "Renny isn't here. He's on a plane that they've sent west with a load of weapons."

The homely chemist was gloomy, feeling let down because they had not found Renny, their companion, who was a hostage, at this spot. Ham was unusually quiet, not even trying to think up remarks that would irritate Monk. Long Tom muttered: "This is a fine break. I thought we had Renny spotted."

Doc whispered: "There are two ways of helping Renny. One of them is to catch the Colorados before Spad Ames can find them. The second is to trail these fellows to the spot where they meet their arms cargo plane, and affect a direct rescue, if we can."

"Kind of puts us up a tree," Monk muttered. "We ain't got no idea where to find the Colorados. And you don't trail airplanes so easy."

"In this case, we might manage," Doc Savage said slowly.

"You mean-somebody stow away aboard?"

"No." The bronze man indicated the radio. "Use that. It is a transmitter as well as a receiver, and the emergency batteries will operate it steadily for almost forty-eight hours. We can trail that transmitter by using another direction-finder."

They concealed the radio far back in the fuselage of one of the planes. Long Tom, who was thinner than any of the others, crawled into the cramped s.p.a.ce and planted the apparatus.On second thought, Doc Savage concluded to put a radio in each of Locatella's ships, so he went back to the taxicab, and worked with the radio that was in the machine. Transmitter and receiver were separate units, although mounted in the same case. He removed the transmitter unit with its compact a.s.semblage of batteries, and replaced the receiver and the case. It now appeared that the taxi radio had not been tampered with. But Doc carried the transmitter unit back, and they installed it in the other plane.

They put this one inside the right wing. Doc carefully unlaced an inspection port, and placed the set far back where it was not likely to be noticed, then replaced the inspection port cover.

"Now," announced Long Tom, "we're ready for them to take off for the west."

"The trouble is," Monk muttered, "they may stick around here for days, trying to catch the Colorados."