One glance at the black, triangular fin slicing through the water was enough. It was a shark of the man-eating variety.

“Get out your gun, Red!” barked Don Winslow, reaching for his own weapon. “Hold it ready, but don’t use it until the last possible moment. The smell of blood—even shark’s blood—will drive the other sharks mad!”

Biting his lips, the stocky lieutenant ripped the waterproof silk from his Navy Colt’s revolver. Though he could have led a landing party in the face of machine gun fire, without a qualm of fear, the idea of becoming shark meat while still alive was hard for Red Pennington to get used to.

“Here’s hopin’ there aren’t any other sharks around!” he gulped. “If I don’t see any in the next two minutes, I’m gonna shoot this one so full of holes....”

“Hold it!” Don Winslow rapped out. “I see another fin—no, it’s three more! And more coming, off there to port. Great guns, Red! We’re right in the middle of a school of them!”

Calmly, he took a squint at the chambers of his revolver making sure they were all loaded.

“You see now, Red, why I wouldn’t take automatic pistols,” he said. “Those things jam up after a little exposure to salt water. These revolvers can take it.”

“Yeah!” responded Red bitterly. “But what good’s all that goin’ to do us if they come too fast for us to shoot? HEY! LOOK OUT! HE’S COMING FOR YOU, DON!”

Twenty feet to starboard, a huge fin was driving straight toward them. In another second the killer shark would roll over for the bite, Don knew.

Instead of firing, however, he brought both arms down flat on the water, with a tremendous splash. At the same time, he yelled like a trapped hyena.

With a quick swirl, the shark changed his course; but even so, it was a close call. So close that the killer’s mighty tail slapped against Don’s legs with numbing force.

“Wha-what’s the big idea?” gurgled Red, twisting his neck to watch the shark’s departure. “You had time to shoot him, Skipper!”

“But not time to stop him!” replied Don. “Anyhow, we don’t want any blood in the water as near to us as that. I guess our best bet is to serve these sharks a breakfast, but keep them as far away as possible. Like this!”

Snapping up his Colt, Don Winslow fired at a circling fin, about forty yards distant. There followed the brief flurry of a wounded shark. Then, without warning, the ocean round about was lashed to a froth. Great bodies whirled and plunged in a circle of bloodstained water. From all sides, the sharp, triangular fins of the other sharks came streaking toward the center of disturbance.

“And that,” gritted Don Winslow, “is the way they’d be bearing down on us, if I’d shot that first would-be man-eater, instead of scaring him! How’d you like to be in the middle of that ring-around-the-rosie, Red?”

“G-golly, no!” shivered the junior officer. “I’ve heard that sharks were cannibals; but I never thought they were such fast feeders. Look, Don! They’ve finished that one already. Eaten him alive!”

“In which case we’d better give them some more breakfast bacon,” agreed the young commander. “Go ahead and shoot, sailor! It’s your turn.”

“Uh-uh, Don! It’s your turn all the time,” the redhead responded. “As a marksman, I’ll never be in your class, and we’ve got to save our bullets. That way, we might keep those sea tigers busy eating themselves until the plane shows up.”

Carefully Don picked his next target and fired. This time his bullet merely clipped through the shark’s back fin, but the wound was enough for its blood maddened fellows. A second savage feast churned the water’s surface, fifty yards away.

One by one Don’s precious cartridges were expended, until only half a dozen were left. The dawn light had grown stronger now, and Red, glancing toward the distant Gatoon, detected movement aboard her.

“They’ve spotted us aboard ship!” he cried. “They’re lowering a boat!”

Don Winslow’s revolver cracked again.

“They’ll get here just about in time,” he commented. “That is, provided I don’t miss any shots. Every shark in ten square miles must have smelled this party and joined it. A number of them have been looking us over, too.”

“I’ve noticed that, Skipper, don’t worry!” Red Pennington exclaimed. “It’s too bad the Scorpion plane didn’t get here sooner, but.... Say! Am I hearing things, or is that a plane’s motor, over to the east?”

Above the splashing rose the snarl of an airplane motor warming up. The sound rose in pitch, then faded abruptly.

“That’s Splendor and his pilot taking off!” remarked Don, his eye on the circling man-eaters. “They’ll climb to ten thousand to start their watch for the bombers. Right now, I envy them!”

For a long, listening moment, there was no sound but the lapping of waves and the occasional splash of a feeding shark. Very gradually the drone of an approaching plane grew louder.

“It’s not Splendor’s motor,” Don decided at last. “Besides, it’s flying too low and straight to be on patrol. It’s the Scorpion seaplane, all right, and headed straight for us!”

“It’ll be here before the boat from the Gatoon!” cried Red Pennington. “Probably the pilot thinks the boat is after a couple of spies. If he does, he’ll beat ’em to it and pick us up! Where is he, though, Don? That motor’s getting close, but there’s no plane in sight!”

“That’s because he’s flying low, right in the 'eye of the sun,’ as they say,” replied the other, whipping up his gun for another shot.

The bullet missed, just as the target dived under. Another slug from Don’s nearly exhausted supply furnished more living “breakfast” for the ravenous sea tigers. Two sharks swirled dangerously close to the two officers in the turmoil.

“Better start splashing and keep it up, Red!” Don Winslow advised. “Those finny devils are getting more curious about us every second. If we can keep them off just a few more minutes....”

CR-RASH! SLAP! SWISH!

The school of sharks scattered in all directions, as a seaplane’s pontoons smashed down into the water close by.

“Ahoy, you two!” cried a voice almost over the swimmers’ heads. “Climb aboard, and make it snappy! Those sharks will be back in a minute.”

Looking up, Don and Red saw that a few strokes would bring them within reach of the plane’s starboard pontoon. So skillfully had the pilot maneuvered his craft in the choppy waves that he was now drifting past almost within arm’s reach. The man’s head and arms were just visible through the cabin door which he had slid back.

Don gripped the pontoon’s wet surface, heaved himself up, and reached an arm down to Red Pennington. His revolver was back in its shoulder holster, but the bulge of it was plain, he knew, under his wet blouse.

“Those sharks nearly got us at that!” he observed, imitating Corba’s whining tones. “We’ve been shootin’ at ’em since daylight, but they was gettin’ uglier every second. An’ then that boat put off from the Gatoon. Between it and the sharks, we wouldn’t have lasted five minutes longer!”

“I know all that, sailor!” snapped the pilot, glancing back at the approaching lifeboat. “Stow the gab and climb up here, so I can take off. They’ve got rifles in that boat!”

Muttering under his breath, the fake Corba clambered into the cabin, with his dripping companion at his heels. As they did so, the seaplane’s motor burst into full-throated sound. Gracefully the ship circled, straightened out over the slapping wave tops, and took off into the wind.

“You, Mink!” called the pilot above the motor’s steady roar. “They tell me you’re good with a machine gun. If you want some practice, move over and man that turret piece!”

“Okay!” replied Red Pennington, taking the role of the gorilla seaman. “But wot’s the idea now? We ain’t gonna attack the Gatoon all by ourselves, are we?”

The seaplane listed steeply in a sharp bank. As it swung back toward the drifting yacht, the pilot laughed harshly.

“We’re going to put a few holes in that lifeboat, just for the fun of it!” he said. “I’ll give ’em a burst from the wing guns, and you finish the job as we leave ’em astern.”

“This job,” cut in Don Winslow’s voice, “is already finished, pilot! Ease over and give me those controls, or take a bullet through your ribs!”

The Scorpion pilot stiffened under the hard pressure of Don’s gun muzzle. His lips drew back in an animal snarl.

“You’re not Corba!” he grated, as the young Navy Commander pulled back on the joystick. “And this other guy isn’t Mink. What’s the game, anyway?”

Red Pennington’s revolver prodded gently between the man’s shoulder blades, as Don banked the seaplane for a fast climb.

“Just a couple of Navy lads taking over for Uncle Sam,” the grinning lieutenant answered. “Your precious pals, Mink and Corba are locked up in the Gatoon’s brig. That’s where we’re going to put you, if we’re lucky in the coming dogfight.”