Doc handed Ham a phone. "Get the nearest army flying field, Ham. See if you can raise me a pursuit ship fitted with machine guns. It's against regulations, but "
"Hang regulations!" Ham snapped, and seized the instrument.
From the blond airport manager Doc learned where the autogyro had gone to meet the man who had put over the trick. The spot was in New Jersey.
Doc located it on the map. It was in the mountainous, or, rather, hilly, western portion of Jersey.
Ham cracked the telephone receiver onto its hook. "They're warming up a pursuit job for you, Doc."
It required less than ten minutes for Doc to ferry over to the army drome, plug his powerful frame into a cockpit, saw the throttle back, and take off. He had a regulation war plane now.
Flying northward, Doc had a fair idea of the purpose of their enemy in decoying the autogyro. The place was within motor distance of New York, so the villainous unknown one would probably be on hand. He would destroy the autogyro, thus hampering Doc and his friends all possible.
"Whoever it is, they're willing to do anything to keep us from getting to that legacy of mine in Hidalgo!" Doc concluded.
Over the Delaware River, Doc dived and tested his machine guns by shooting at the shadow of his plane on the water.
Knobby green hills sprang up underneath. Doc used a pair of binoculars to scrutinize the terrain.
Farmhouses were scattering, ramshackle. Very few of the roads were paved.
Doc discovered his autogyro at last.
The windmill plane sat in a clearing. Near by ran a paved road.
In the clearing with the plane was a green coupe and two men. One of the men was holding a gun upon the other.
The gun wielder, Doc perceived when he came nearer, was masked. The man discovered Doc's army pursuit plane, diving with motor cans a-thunder. The fellow took fright.
Deserting the other man, who must be the autogyro pilot, the masked fellow raced to the windmill plane. The gun in his fist spat a bullet into the fuel tank of the plane. Gasoline ran out in two pale strings. The masked man struck a match and tossed it into the fuel. Instantly the autogyro was bundled in hot flame.
One thing Doc noted about the masked man the fellow's fingers were a deep scarlet hue for an inch of their length!
The man was also squat and wide. He ran with shortlegged, pegging steps for the green coupe, dived into it. The green car ran out of the field like a frightened bug.
Doc's cowl machine guns released a spray of lead that forked up dust behind the coupe. The car skewered onto the road and turned north.
Again Doc's Browning guns tore off their ripping cackle of death. After the army fashion, every fifth bullet in the ammo cans was a phosphorous-filled tracer. These burst with hot red blots directly behind the green coupe.
Slowly, inexorably, the gray cobwebs of tracer smoke climbed into the rear of the automobile.
With a wild swing, the green car suddenly left the pavement. It vaulted a ditch, miraculously remaining upright, and skewered to a stop amid tall bush that practically hid it.
Doc distinctly saw the passenger quit the car and take to the concealment of the timber.
A couple of times Doc dived and let the Browning guns spew their twelve hundred shots a minute into the timber. He did it more to give the masked man one last scare than from any hope of bagging the fellow. The timber offered perfect concealment.
Not a little disgusted, Doc landed and launched a hunt afoot for the masked man. But it was too late.
The airport attendant who had flown the autogyro here could give no worthwhile description of the masked man when Doc consulted him. The fellow had merely sprung out of the green car with a gun.
Doc telephoned the authorities and had a net spread for the masked man before he took off again for Washington. But he was pretty certain the fellow would evade the Jersey officers. The man was smart, as well as very dangerous.
Doc took the chagrined airport attendant with him in the army pursuit plane back to Washington.
Ham and the others were waiting when Doc arrived, after restoring the pursuit plane to the army field.
"Have any trouble getting our papers up?" Doc asked.
Ham tightened his mobile, orator's mouth. "I did have a little trouble, Doc. It was strange, too. The Hidalgo consul seemed very reluctant to 0. K. our papers. At first he wasn't going to do it. In fact, I had to have our own secretary of state make some things very clear to Mr. Consul before he gave us the official high sign."
"What's your guess, Ham?" Doc asked. "Was the official directly interested in keeping us out of Hidalgo, or had some one paid him money to make it tough for us?"
"He was paid!" Ham smiled tightly. "He gave himself away when I accused him of accepting money to refuse his 0. K. on our papers. But I was not able to learn who had put the cash on the line."
"Somebody!" Renny rumbled, his puritanical face very long. "Somebody is taking a lot of trouble to keep us out of Hidalgo! Now, I wonder why?"
"I have a hunch!" Ham declared. "Doc's mysterious heritage must be of fabulous value. Men are not killed and diplomatic agents bribed without good reasons. That concession of several hundred square miles of mountainous territory in Hidalgo is the explanation, of course. Some one is trying to keep us away from it!"
"Does anybody know what they raise down in that neck of the woods?" Monk inquired.
Long Tom hazarded a couple of guesses, "Bananas, chicle for making chewing gum "
"No plantations in the region Doc seems to own," Johnny, the geologist, put in sharply. "I soaked up all I could find on the precise region. And you'd be surprised how little it was!"
"You mean there was not much information available about it?" Ham prompted.
"You said it! To be exact, the whole region is unexplored!"
"Unexplored!"
"Oh, the district is filled with mountains on most maps," Johnny explained. "But on the really accurate charts the truth comes out. There's a considerable stretch of country no white men have penetrated. And Doc's strange heritage is located slap-dab in the middle of it!"
"So we gotta play Columbus!" Monk snorted.
"You'll think Columbus's trip across the briny was a pipe when you see this Hidalgo country!" Johnny informed him. "That region is unexplored for only one reason white men can't get into it!"
Doc had been standing by during the exchange of words. But now his calm, powerful voice commanded quick attention.
"Is there any reason we can't be on our way?" he asked dryly.
They took off at once in the monster, low-wing speed plane. But before their departure, Doc telephoned long distance to Miami, Florida, where he got in touch with an airplane-supplies concern. He ordered pontoons for his plane, after determining the company kept them in stock.
The approximately nine-hundred-mile flight to Miami they made in something more than five hours, thanks to the tremendous cruising speed of Doc's superplane.
Working swiftly, with lifting cranes and tools and mechanics supplied by the plane-parts concern, they installed the pontoons before darkness flung its pall over the lower end of Florida.
Doc taxied the low-wing speed ship out over Biscayne Bay a short distance, making sure the pontoons were seaworthy. Back at the seaplane base he took on fuel and oil from a seagoing filling station built on a barge.
To Cuba was not quite another three hundred miles. They were circling over Havana before the night was many hours old. Another landing for fuel, and off again.
Doc flew. He was tireless. Renny, huge and elephantine, but without equal when it came to angles and maps and navigation, checked their course periodically. Between times he slept.
Long Tom, Johnny, Monk, and Ham were sleeping as soundly among the boxed supplies as they would have in sumptuous hotel beds. A faint grin was on every slumbering face. This was the sort of thing they considered real living. Action! Adventure!