"Take the controls," Doc Savage told Renny.

Renny remonstrated: "Hey — what on — "

Then he made a leap for the controls. Doc had deserted them. Renny banked the plane in a circle. Like all of Doc's five friends, he was an excellent pilot. Doc's teaching had made accomplished airmen out of them. Doc seemed able to impact a share of his own genius to those whom he taught.

Doc now snugged a parachute harness about his powerful frame. He grasped the valve which was all-important to the safety of the submarine.

Before the others could voice an objection, Doc shoved open the cabin door. He dived through.

The white silk of the parachute came out of the back pack like a puff of pale smoke. Doc was lowered to the ice near the distressed Helldiver.

Ben O'Gard and his crew held guns. They made threatening gestures. Doc displayed the valve. This was the magic wand that quieted the villains.

"Throw your weapons overboard!" Doc commanded.

For this order, he was roundly cursed. Ben O'Gard waxed especially eloquent. He must have gathered swear words from most of the dives of the world. He swore in six distinct languages, not counting pidgin English.

But the guns went overboard.

DOC SAVAGE now sprinted forward. The ice had closed in perceptibly. But more than a score of feet still separated the Helldiver from the remorseless blue jaws.

The surface of the floe was slippery. The leap to the submarine was prodigious. But from the ease with which Doc made it, he might have been gifted with invisible wings.

More than one gasp of awe escaped from the gullets of the Helldiver villains as they witnessed the great leap. They recoiled from the mighty bronze man. They still remembered what a child their huge walrus of a leader had been in those bronze hands.

One thug even backed away so hastily he fell overboard. He squealed like a rat in the icy water until he was hauled back on deck.

Not a minute could be wasted. Doc hardly touched the steel deck before he was gliding through the intricate insides of the submarine.

Doc worked swiftly at replacing the valve.

Ben O'Gard's men flocked around him like children. They already had the deck hatches closed in readiness.

Even Ben O'Gard himself came fawning up with a wrench to assist in the work. But Doc waved him aside. His bronze fingers were more speedy than any wrench — and they could tighten a tap just about as snugly.

"All clear!" Doc called at last. "Fill the main tanks!"

The crew flocked to station. The electric motors started. With a windy gurgle that was nothing if not joyful, the Helldiver eased down out of the fearsome blue jaws of ice.

Doc watched the valve for a moment. Satisfied it was not going to leak, he turned away.

At that instant, the steel door of the compartment in which he crouched clanged shut. The dogs which secured it rattled fast.

He was imprisoned!

DOC SHRUGGED. He sat down on a convenient pipe. He was not worried. He was armed.

True, Ben O'Gard and his crew probably had guns themselves, by now. The weapons they had thrown overboard so profanely at Doc's request had hardly comprised their entire armament. They were too wily for that.

But Doc had the explosive he always carried in his pair of extra molars. With it, he could speedily blast open the bulkhead.

And once the sub came to the surface, he had simply to unscrew the valve — and he would have the gang at his mercy again.

The electric motors set up a musical vibration. The Helldiver had slanted down steeply in its hurried dive. Now it trimmed level. After a time, it sloped upward perceptibly. There came a jar as it touched the underside of the ice pack.

Other crunching shocks ensued. They were of lesser violence. The submarine was feeling blindly for another spot free of ice. This continued interminably. Open leads seemed to be very scarce.

Doc got up and rapped tentatively on the thick steel bulkhead.

He was cursed. He was told he would be killed if he didn't behave. He was promised all kinds of dire fates.

This didn't worry him much. Danger seldom worried Doc. A telegraph operator in a great relay office becomes accustomed to the uproar of instruments about him. A structural steel worker comes to think nothing of the fact that a single misstep means sudden death.

By the same token, Doc Savage had haunted the trails of those who sought his violent end for so long that he took danger as a matter of course.

More than an hour passed. Doc became impatient.

Finally, the submarine arose to the surface. The stopping of the electric motors and the starting of the oil-burning Diesel engines showed that.

Doc promptly removed the all-important valve.

Through the steel bulkhead, he informed Ben O'Gard what he had done.

He got a surprise. Ben O'Gard gave him the horse laugh.

Doc was puzzled. He had thought he held an ace. But the missing valve seemed to worry his enemies not at all. There was but one explanation.

They had found a snug harbor on the uncharted coast! Doc settled down to await developments. They came twenty minutes later.

There reached his ears a sound like six or seven hard hailstones tapping the submarine hull.

Doc knew what it was.

Machine-gun bullets.

Were his friends starting hostilities? He hoped not. They'd fool around and get themselves shot out of the air. The old seaplane was no battle wagon.

With a jarring bedlam, the Diesel engine sped up. The mad race of the vertical-trunk pistons vibrated the whole submarine. The Helldiver lunged away soggily.

Next instant came a shock which, catching Doc by surprise, piled him against a bulkhead.

The Helldiver had gone aground.

Men yelled. They sounded like chicks cheeping in an incubator. A machine gun cut loose on deck. Another joined it. Their clamor was hollow, like crickets shut up in a can.

This continued for the space of time it would take a man to count to several hundred.

Wham! The sub all but rolled completely over. The plates shrieked. Loose tools jumped about as beans in a shaken box.

Doc picked himself up.

"I'd better hold onto something," he remarked to no one in particular.

A bomb had just exploded in the water near the submarine. Doc shook his head slowly. His friends had no bombs! Ben O'Gard's bellow penetrated the bulkhead. "Come out!" he boomed. "You gotta help us!"

"Go take an ice bath!" Doc suggested.

Ben O'Gard spewed profanity hot enough to melt the steel bulkhead.

"Rust my anchor, matey!" he yelled at last. "You've got the upper hand on us again. We'll do anything you say, only you gotta help us."

"It sounds like you're aground," Doc told him. "My replacing the valve won't help any now."

"T' hell wit' the valve!" roared Ben O'Gard. "Ain't none of us swabs can fly the foldin' seaplane. You gotta take the sky hooker up an' fight off them buzzards that's bombin' us!"

"Who's bombing you?" Doc questioned.

"Keelhaul de Rosa's gang — the dirty deck lice."

DOC DIGESTED this. It was an entirely new development. Since the Helldiver had left New York, there had been nothing to show Keelhaul de Rosa still existed upon the earth. Now the explanation for that was plain.

Keelhaul de Rosa had one of the treasure maps. He had secured a plane and flown to the wreck of the liner Oceanic. And now he was seeking to wipe out his rivals.

"Stand away from the door," Doc ordered. "I'll come out." The dogs securing the steel panel clanked free. Doc swung the panel open. Several of Ben O'Gard's villains faced him. But not a gun was turned in his direction. They were a scared lot.