"As I recall," Doc continued, "Thunder Island is nothing but the cone of an active volcano projecting from the sea. The sides of the cone are so barren they support no vegetation whatever. And great quantities of steam come continually from the active crater."

"Exactly," corroborated Bittman. "Jerome Coffern told me he flew over the crater once with Yuder. The crater was a number of miles across, but the whole thing seemed filled with steam and fumes. They brought back specimens from the cone, however. Jerome Coffern turned them over to the largest college of geology in New York City."

"We’re getting off the trail," Doc declared. "You said you noted something suspicious about Yuder’s actions. What was it?"

"After he and Jerome Coffern returned from Thunder Island, Yuder was surly and furtive. He acted like he had a secret, now that I think back. But at the time, I thought he was in an ill temper because he had found no oil, although he scouted Thunder Island the whole time Jerome Coffern was there gathering specimens."

"Hm-m-m," Doc murmured.

"I’m afraid that does not help much," Bittman apologized.

"It’s too soon to say."

Doc thought briefly. Then he nodded at the telephone.

"May I make a call from here?"

"Of course!"

Arising hastily, Bittman left the room. This politeness was to show he had no desire to listen in on Doc’s phone talk.

Doc called a number.

"Monk?" he asked.

A mild, pleasant voice replied, "Sure thing, Doc."

That mild voice was a deceptive thing. A listener would not have dreamed it could come from the kind of a man who was at the other end of the wire. For the speaker was Lieutenant Colonel Andrew Blodgett Mayfair.

He was a two-hundred-and-sixty-pound human gorilla. He was one of the roughest and toughest and most likable and homely men ever to live. Monk was also one of the few chemists in the world who could be considered a greater expert in that line than poor, unfortunate Jerome Coffern.

Monk was one of five men who accompanied Doc Savage on his amazing jaunts in pursuit of adventure. These five, like Doc, were giving their lives to traveling about the world and righting wrongs and handing out their own brand of justice. Whatever excitement turned up in the course of that pursuit — and there was always plenty — they gobbled up and liked it. How they liked it!

"Monk," Doc suggested, "could you take on a little trouble right now?"

"I’m on my way!" chuckled Monk. "Where do I find this trouble?"

"Call Renny, Long Tom, Johnny and Ham," Doc directed. "All of you show up at my place right away. I think I’m mixed up in something that will make us all hump."

"I’ll get hold of them," Monk promised.

DOC stood by the phone a moment after hanging up. He was thinking of his five friends, "Monk," "Renny," "Long Tom," "Johnny," and "Ham." They were probably the most efficient five men ever to assemble for a definite purpose. Each was a world-famed specialist in a particular line.

Renny was a great engineer, Long Tom an electrical wizard, Johnny an archaeologist and geologist, and Ham one of the cleverest lawyers Harvard ever turned out. The gorillalike Monk, with his magical knowledge of chemistry, completed the group.

They had first assembled during the Great War, these adventurers. The love of excitement held them together. Not a one of the five men but owed his very life to the unique brain and skill of Doc.

With Doc Savage, scrapper above all others, adventurer supreme, they formed a combination which could accomplish marvels.

Doc went in search of Oliver Wording Bittman. He found the famous taxidermist in an adjoining room and thanked him for use of the phone.

"I must take my departure now," he finished. "I should like greatly, though, to discuss at some time your association with my father. And any service I can perform for you, a friend of my father’s, a man who saved his life, I shall gladly do."

Oliver Wording Bittman shrugged. "My saving of your father’s life was really no feat at all. I was simply there and shot a lion as it charged. But I would be delighted to talk at length with you. I admire you greatly. Where could I get in touch with you?"

Doc gave the address of a downtown New York skyscraper which towered nearly a hundred stories — a skyscraper known all over the world because of its great height.

"I occupy the offices formerly used by my father on the eighty-sixth floor," Doc explained.

"I have been there," Bittman smiled. "I shall look you up." He gestured at an extension telephone. "May I not call you a taxi?"

Doc shook his head. "I’ll walk. I want to do some thinking."

Down on the street once more, Doc strode across traffic-laden Central Park West and entered the Park itself. He followed the pedestrian walk, angling southeast. He did not try to make haste.

His remarkable brain was working at top speed. Already, it had evolved a detailed plan which he would put in operation as soon as he met his five friends at the skyscraper office.

High overhead, a plane was droning. Doc looked up as a matter of course, for few things happened around him that he did not notice.

The craft was a cabin seaplane, a monoplane, single-motored. And it was painted green. It circled, seemingly bound nowhere.

Doc dismissed it from his thoughts. Planes circling over New York City were a more common sight than the discovery of an ordinary horsefly.

The walk he traversed descended steeply. It crossed a long, narrow bridge over a Park lagoon. The bridge was of rustic log construction.

Doc reached the bridge middle.

Unexpected things then happened.

With a loud bawl of exhaust stacks, the seaplane above dived. Straight down it came. There was murderous purpose in its plunge.

Doc Savage did not have time to race to the end of the bridge. Had he done so successfully, there was no shelter to be had.

A bronze flash, Doc whipped over the rustic railing. He slid under the bridge.

An object dropped from the plane. It was hardly larger than a baseball.

This thing struck the bridge squarely above where Doc had gone over.

A gush of vile grayish smoke arose. With incredible speed, the bridge began dissolving!

THE weird phenomenon, as the rustic bridge was wiped out by the fantastic Smoke of Eternity, was even more striking than had been the dissolution of Jerome Coffern’s body.

The metallic capsule bearing the Smoke of Eternity had splashed the strange stuff some distance in bursting. A great section of the bridge seemed to burn instantly. But there was no flame, no heat.

The play of electrical sparks was very marked, however. In such volume did they flicker that their noise was like the sound of a rapidly running brook.

The Smoke of Eternity, after passing through and destroying the bridge, next dissolved the water below. So rapidly did the eerie substance work that a great pit appeared in the surface of the lagoon.

Water rushing to fill this pit, formed a current like a strong river.

It was that current which offered Doc Savage his only real threat. For Doc had not lingered under the bridge. With scarcely a splash, he had cleaved beneath the surface. Guessing what was to come, he swam rapidly away.

Doc’s lungs were tremendous. He could readily stay under water twice as long as a South Sea pearl diver, and such men have been known to remain under several minutes. He swam rapidly down the lagoon, keeping close to the bottom and stroking powerfully to vanquish the current.

Overhead, the seaplane circled again and again. The only occupant, the pilot, peered out anxiously.