His little eyes popped in astonishment.

Under the concealment of the smoke screen, a great steel tank of a thing had come up from the deep river bed. This was in the nature of a submarine, but without conning tower or engines and propellers.

A steel hatch gaped open in the middle of the tank. Into this hatch Monk was hauled.

The seaplane taxied away. The hatch closed. The tank of a submarine sank beneath the surface, submerging after the fashion of a genuine U-boat.

The whole operation had been blanketed by the smoke screen. An observer would not have dreamed a man had been shifted from the plane to a strange underwater craft which now rested on the river bed.

Kar’s men dragged Monk into a tiny steel chamber.

For a minute or two, the loud, sobbing gurgling of water entering the ballast tanks persisted. The submersible rolled a little, then settled solidly on the river bottom. One of the gang now spun metal wheels. These, no doubt, controlled valves.

The interior of the strange craft became quiet as a tomb, except for a monotonous drip-drip-dripof a leak somewhere.

The men were taking no chance on Monk’s escape. Three of them stood apart and kept pistols pointed at him.

One fellow picked up an ordinary telephone. This obviously was connected to a wire that led ashore, probably along the cable which must anchor this unusual vessel.

"Kar," he said into the mouthpiece. "We got the big guy here now."

So quiet was the interior of the steel cell that the metallic voice from the receiver diaphragm was plainly audible to every one.

"Let me talk to him," Kar commanded.

THE receiver was jammed against Monk’s scarred ear, but tilted so the others could hear. They held the mouthpiece a few inches from his lips.

"Well, say your piece!" Monk roared.

"You will speak with civility!" snarled the voice from the phone.

Monk blew air out between his lips and tongue, making a loud and insulting noise known variously as the Bronx cheer and the razzberry.

He was kicked in the barrel of a chest for his performance.

"I fear you are going to come to an unfortunate end very soon," Kar sneered silkily.

Monk’s brain was working rapidly, despite his rowdyism. This voice had an ugly, unreal rasp. He knew Kar must be pulling his mouth out of shape with a finger as he spoke, thus disguising his voice.

"What d’you want?" Monk demanded.

"You will write a note to your friend and chief, Doc Savage. The note will tell him to meet you at a certain spot."

Monk snorted. "You want me to lead Doc into your trap, eh? Nothin’ stirrin’!"

"You refuse?"

"You guessed it!"

There ensued a brief silence. Kar was thinking.

"Give me the addresses of the men you call Renny, Long Tom, Johnny, and Ham!" he commanded. "I learned from a chemical supply firm where you lived. That is how my men came to be waiting for you to appear. But I could not find where the other four of your friends reside. You will give me that information!"

"Sure," Monk growled. "Just watch me do it!"

Then his pug nose wrinkled as he thought deeply. He asked a question: "How did you know our names? How did you find Renny, Long Tom, Johnny, Ham, and I always join Doc Savage when he tackles trouble?"

Kar’s voice rattled an ugly laugh.

"The information was simple to obtain!"

"I’ll bet it was!" Monk snorted. "Not many people know we work together!"

"I already knew that Doc Savage has his New York headquarters on the eighty-sixth floor of a skyscraper," Kar rasped. "I simply sent one of my men to strike up a conversation with the elevator operators of that skyscraper. My man learned you five men were often with Doc Savage. He wormed your nicknames from the elevator operators."

"What’s behind all this?" Monk questioned.

Monk did not, of course, know anything about Kar’s sinister purpose. He did not even know of the existence of the weird and horrible Smoke of Eternity.

"Doc Savage has interfered with my plans!" Kar gritted. "He must die! You five who are his friends would try to avenge his death. So you also must die!"

"You don’t know what you’re tryin’ to do!" Monk declared.

"I do!"

"Oh, no, you don’t! You’d be runnin’ like hell if you knew what a terror Doc Savage is when he gets on the trail of a snake like you!"

This drew a loud snarl from Kar. "I do not fear Doc Savage!"

"Which shows you ain’t got good sense!" Monk chuckled.

"Put him in the death chamber!" Kar commanded angrily.

The telephone was plucked from Monk’s furry hands. He was hauled aft.

Evidently Kar was enough of a judge of character to realize he could never force Monk to lead Doc Savage into a death trap. So he was going to get rid of Monk immediately.

ONE of the men twisted metal dogs which secured a hatch-like steel panel in a wall of the submerged tank. This swung back. It revealed a box riveted to the hull. The box had the dimensions of a large trunk. It barely accommodated Monk’s bulk as he was jammed inside.

At the end of the box was another steel hatch. But this was obviously secured tightly on the outside.

A small petcock protruded from the box ceiling. One of Kar’s men opened this with a key. He fitted a grille over it.

A thin stream of water entered.

The hatch into the tanklike craft clanked shut. The dogs rattled loudly as they were secured.

Monk flounced about, wrenching at his manacles. He could not snap them with all his prodigous effort.

He tried to stop the inrush of water through the petcock. He failed. The petcock construction was such that he could not block it, due to the grille covering.

The water had risen above his ankles by now. The clammy wetness was like the creep of death.

Monk beat the steel plates of the outer hatch with his shackled legs. They held. Nothing less than nitroglycerin could shatter them.

Steadily, the water crawled upward. The minutes were passing with agonizing speed for Monk. He perspired. His brain raced. He could evolve no possible scheme of escape.

The river water now covered his mouth. He had his head rammed tightly against the roof plates. It could go no higher. Over his upper lip, the deadly liquid sloshed.

After the fashion of a diver, Monk determined to take a couple of quick inhalations, then draw in a lungful of air. He was going to hang on as long as he could.

But with the first indraw of air, water was sucked into his lungs.

Gagging, choking, he sank helplessly to the bottom plates.

Monk was drowning! There was nothing he could do to save himself; no way to inform Doc to get aid.

However, while Monk had been taken captive, during the time required for the trip up the river, Doc Savage was not idle. Monk’s failure to appear was evidence that something was wrong — and Doc never let anything stay wrong for long!