All through July the Tarpaulin Islanders had been troubled with dogfish. Beginning with a few scattering old "ground dogs," which apparently live on the banks the year round, they had become more and more numerous as the month advanced. Bait was stripped from the hooks; fish on the trawl were devoured until only heads and backbones were left; and the robbers themselves were caught in increasing numbers. At last their depredations became unbearable.

Jim and Percy had made a set one foggy morning on Medrick Shoal. When the trawl came up it was a sight to make angels weep. For yards at a stretch the hooks were bare or bitten off. Then came "dogs" of all sizes from "garter-dogs," or "shoe-strings," a foot long, to full-grown ten-pounders of about a yard. Mingled with them was an occasional lonesome skeleton of a haddock, cusk, or hake.

"Look at the pirate!" said Jim.

Grasping a ganging well above the hook, he held the fish up for Percy's inspection. It was two feet long, of a dirty gray color, slim, shark-shaped, with mouth underneath. Before each of the two fins on its back projected a sharp horn.

"Think of buying perfectly good herring at Vinalhaven, and freighting 'em way down here to feed a thing like that!" mourned Jim. "He's the meanest thief that ever grew fins. Swims too slow to catch a fish that's free; but good-by to anything that's hooked, if he's round. He'll gouge out a piece as big as a baseball at every bite. I'd hate to fall overboard in a school of 'em."

"Don't touch him!" he warned, hastily, as Percy reached out an investigating hand. "He'll stick those horns into you, and they're rank poison."

"Aren't dogfish good for anything?" asked Percy.

"Not a thing! No, I'll take that back. They can be ground up for fertilizer; their livers are full of oil; and their skin makes the finest kind of sandpaper for cleaning or polishing metal without scratching it. They've been canned, too, under the name of grayfish; but no fisherman'd ever eat 'em; he knows 'em too well."

Rod after rod of trawl yielded the same results.

"I'm almost tempted to save my buoys and anchors, and cut all the rest away," announced Jim in disgust. "I've known it to be done. They wear the line out, sawing across it. But I guess the best way is to save what we can and stop fishing for a while. Sometimes they come square-edged, like a stone wall, just as they have this morning; and in a few days they'll have gone somewhere else. Hope it'll be that way this time!"

It was almost noon before the whole trawl was aboard. It had yielded barely two hundred pounds of hake.

"Tell you what!" exclaimed Jim as he looked at his compass and headed the Barracouta westward through the fog for home, "we'll put the trawl in the house for a few days, and fit up for swordfishing. There's a good ground fifteen miles south of the island. I've been down there with Uncle Tom. If we could get some fair-sized fish, it'd be worth our while to take 'em into Rockland."

That afternoon they mustered their swordfish gear. In the house were three or four of the wrecked coaster's mast-hoops. One of these Jim lashed to the sloop's jibstay, about waist-high above the end of the bowsprit.

"That'll do for the pulpit!"

Near the jaws of the gaff he nailed a little board seat, rigged like a bracket on a roof for shingling. On this the lookout could sit, his arm round the mast, watching for fins.

"Now for a harpoon!"

Across the rafters inside the house lay a hard-pine pole eighteen feet long, ending in a tapering two-foot iron. Strung on a fish-line hanging from a spike were a half-dozen swordfish darts. These were sharp, stubby metal arrows, all head and tail and no body, with a socket cast on one side to admit the top of the pole-iron. Back of the arrow-head was a hole, through which was fastened the buoy-line.

"Righto!" exclaimed Jim. "Now when the fog clears we'll be ready to do business."

That very night the mists scaled away before a brisk north wind. Morning showed the sea clear for miles, though a fleecy haze still blurred the southern and eastern horizon.

"We'll take this chance," decided Jim. "May not get a better. Remember it's dog-days!"

At five o'clock they started south. Before eight they were on the swordfish-grounds. The wind, blowing against the long ocean swell, raised a fairly heavy sea. Though the day was clear, they could still feel the fog in the air.

Jim allotted the company their several stations.

"Budge, you swarm up to that seat on the gaff and watch out for fins! Throppy, you steer as Budge tells you! Stand by to take the dory, Perce, and go after any fish I'm lucky enough to iron. Filippo, be ready to throw that buoy and coil of warp off the starboard bow the minute I make a strike. I'll get out in the pulpit with the harpoon. Keep alive, everybody! We're liable to run across something any minute."

Perched aloft, Budge scanned the tossing, glittering sea. His keen eye detected a triangular, black membrane steering leisurely through the waves a hundred yards ahead.

"Fin on the starboard bow! Keep her off, Throppy!"

In a short time the Barracouta was close behind the unconscious fish.

From the bowsprit end burst a shout of disgust:

"No good! I can see him plain! Tail's too limber! Only a shark! Swing her off, Throppy!"

"How can I tell a shark from a swordfish?" Budge called down to Jim.

"Shark's back fin is shorter and broader, and he keeps his tail-fluke whacking from side to side. Swordfish has two steady fins, stiff as shingles; front one is long and slender and curves back on a crook; the after one is the upper tail-fluke. Try again!"

Five minutes passed. Then an excited yell:

"Fin to port!"

Following Budge's shouted directions, the sloop gave chase. Soon they were near their quarry.

"Swordfish!" breathlessly announced Jim. "And a big one! Put me on top of him, Budge!"

Leaning against the mast-hoop that encircled his waist, he lifted the long lance and poised it for the blow. The tail of the fish was almost under his feet when he launched the harpoon with all his strength.

Unluckily, at just that moment the sloop dipped and met a big sea squarely. Her bowsprit dove under, burying Jim almost breast-deep, spoiling his aim. The dart struck the fish a glancing blow on the side of the shoulder. Off darted their frightened game.

Jim gave a cry of disappointment.

"Too bad! Ten feet, if he was an inch! Well, better luck next time!"

A quarter-hour passed. Budge strained his eyes, but no fin! The breeze was shifting to the northeast. Jim cast a practised eye about the horizon.

"If the wind swings round much farther it'll bring the fog again. See anything, Budge?"

"No—yes! Up to starboard! Right, Throppy! Keep her as she is!"

The fish was swimming at a moderate rate, and the sloop had no trouble in catching up with him. The two stiff fins betrayed him.

"Swordfish all right!" muttered Jim. "Not quite so big as the other one, but too good to lose! Steady, Throppy!"

Foot by foot the Barracouta's bowsprit forged up on their prospective prey. Nobody spoke. Jim's grip on the pine staff tightened; his eye measured the distance to the dull-blue shoulder.

Six inches further ... five ... four ... three ... two ... one ... now!

With all his might he drove the harpoon downward, straight for its mark. There was a tremendous flurry, and down went the fish, leaving a trail of blood.

"Got him that time! Right through the shoulder! Over with that warp and barrel, Filippo!"

The Italian obeyed, his eyes wide as saucers. Soon the coils of the fifty-fathom lobster-warp had straightened out in the wake of the terrified fugitive, and the red buoy danced off over the wave-crests.

"He's up to you, Perce!" shouted Jim. "Go after him! Only be sure to remember what I told you coming out. Keep your eye on the barrel! Haul it aboard as soon as you can, and coil in the warp. Don't get snarled up in it if he starts running again."

Percy drew the dory alongside and jumped in. Meanwhile the harpoon staff was dragged aboard by the line attached to it, the pole-iron having pulled out of the socket in the dart when the fish was struck. Jim stuck on a fresh dart, attached to another warp and buoy, and was ready for a second strike.

"Pass Percy that lance, Filippo!" he ordered.

"He may need it to keep off the sharks."

The Italian handed to Whittington a short, stout pole, on its end a two-foot iron rod, flattened to a point shaped like a tablespoon, and filed to razor sharpness. Percy set out in pursuit of the red barrel, now almost two hundred yards to starboard.

"Another fin to port!" hailed Budge; and the Barracouta sheered off in quest of a second prize.

For the first few minutes, though Percy rowed his prettiest, he could not hold his own with the moving barrel. Each glance over his shoulder showed that it was farther away. He bent stoutly to his oars. The sloop was heading in the opposite direction, and the distance between them widened rapidly. The wind had veered still further to the east and the fog hung more thickly on the horizon.

The barrel was nearer. At last he had begun to gain on it. He rowed with renewed vigor. Either the fish was tiring out or had stopped swimming altogether. Presently the dory bumped against the keg.

Pulling in his oars and dropping them over the thwarts, he sprang forward and gaffed the buoy. A moment later he had lifted it aboard and was pulling in the warp.

The first ten feet came over the gunwale without any resistance; then he had to surge against the sag of a dead weight. The fish had either given up the ghost or was too exhausted to struggle.

Fifty fathoms is a long distance to drag two hundred pounds. Percy's arms began to ache before he had coiled in half the warp. Then he was treated to a surprise.

Several feet of line jerked through his hands. The fish had come to life again!

Percy closed his grip on the strands, but soon let them slip to avoid being pulled overboard. He started to make the line fast, but remembered Spurling's caution against the danger of tearing the dart out of his prey. So he tossed the barrel over again and began rowing after it.

After traveling a few rods, it stopped. Once more he took it aboard and began coiling in the warp. This time the fish must surely be spent. But no! Thirty fathoms had crossed the gunwale when the rope was whisked from his hands with even more violence than before.

Taken completely by surprise, Percy was wrenched forward. He hung for a moment over the side, twisted himself back in a strong effort to regain his balance, and incautiously planted his foot inside the unlaying coil. A turn whipped round his ankle, and he was snatched overboard, feet first.

Before he could make a motion to free himself he was plowing rapidly along under water. His first panic passed. Unless he wished to drown, he must somehow clear his foot of that vise-like grip. And whatever he did must be done at once.

He tried to reach his ankle, but the rate at which he was traveling straightened out his body, and he could not bend it against the water rushing by him. The warp leading back to the dory trailed across his face. He felt his way down it, hand over hand, to his ankle.

There was a terrible pressure on his chest, a roaring in his ears; he was strangling. He could not hold his breath ten seconds longer.

Bent almost double, he grasped the taut line beyond his foot, first with one hand, then with both, and flung his whole weight suddenly on it in a desperate pull.

The strain round his ankle eased, the rope loosened. Kicking vigorously, he freed himself from the loop. Then he let go of the warp and quickly rose to the surface.

Percy was a good swimmer. He cleared the water from his mouth and nose, paddled easily while he drew two or three long breaths, then raised himself and looked around.

Twenty yards away the dory bobbed aimlessly, the rope still running at a rapid rate over its gunwale. As Percy rose on a wave he caught a glimpse of the Barracouta more than a mile off; engrossed in the chase of the second fish, her crew had probably not observed his mishap. He turned his eyes back to the dory at the very moment that the warp ran out to its full length and the barrel was whirled overboard.

Its red bilge flung the spray aloft as it towed rapidly toward him. Ten yards away it came to a sudden stop. The swordfish was either dead or taking another rest.

It was a matter of no great difficulty for Percy to reach the little cask. He rested on it for a moment, then resumed his swim toward the boat. Presently he was grasping the gunwale.

A month earlier it would have been absolutely impossible for him to scramble into the high-sided, rocking craft. As it was he had a hard fight, and he was all but spent when he tumbled inside and lay panting.

When he raised himself, the first thing he noticed was that the fog was driving nearer. The wind was now due east. It promised to bring the day's fishing to an early end. He must retrieve the barrel and get the fish aboard as soon as possible or he might lose it altogether.

Shipping his oars, he rowed up to the cask and took it in. A pull on the warp showed that the swordfish was motionless. Percy began hauling again, but this time he was very careful to keep his feet clear of the coil.

A damp breath smote his cheek. He glanced toward the east, and saw the fog blowing over the water in ragged, fleecy masses. The Barracouta was momentarily hidden. When she reappeared, fully a mile distant, her crew were hoisting a black body aboard. While he was fighting for life they had succeeded in capturing the second fish. The sight reminded him of his duty. He resumed pulling.

As the fathoms came in there was no sign of life on the other end. The fish sagged like lead. At last the long drag was over and its body floated beside the dory.

"Deader 'n a door-nail!" muttered Percy.

His prize was fully seven feet long. The iron had gone down under the shoulder and out into the gills, causing it to bleed freely. Its sword, which was an extension of the upper jaw, suggesting a duck's bill, was notched and battered, where it had struck against rocks on the bottom.

Following Jim's directions, Percy fastened a bight of the warp securely round the tail of his prize, triced it up over the dory's stem, and made the line fast round a thwart. The fish was so heavy that he could not lift it very high, and most of its body dragged in the water. He began to row slowly toward the sloop.

Thicker and thicker blew the fog. Finally it blotted out the Barracouta; but Percy's last view of her told that she was heading his way. What if she could not find him! The thought gave him an unpleasant chill. He rowed harder.

A splash astern attracted his attention. A violent shock set the dory quivering. He started up just in time to see a large fish dart away, leaving the blood streaming from a gory wound in the head of the swordfish.

A shark! Percy knew he was in for a fight. He seized the lance and sprang into the stern.

A black fin shot alongside. The marauder rolled up for his turn at the banquet. Just as his jaws opened Percy drove the keen steel into his throat.

Mad with fright and pain, the robber flashed off, thrashing the bloody water. Another fin appeared on Percy's left. Again he lunged, and found his mark. The tail of the wounded shark struck the dory a heavy blow. Down it rolled, almost pitching the boy overboard head foremost among the blood-crazed sea-tigers. For a moment he sickened at what might have happened; but he regained his balance and hung to the lance. His fighting blood was roused. He had risked too much already to have the swordfish torn to pieces under his very eyes.

Knees braced tightly against the sides of the stern, hands locked round the stout butt of the lance, he foiled rush after rush of the black-finned, white-bellied pirates. Again and again he lunged and stabbed, until the water round the rocking boat was dyed crimson.

There seemed to be no end to the sharks. Fins crisscrossed the water all about and cut in toward the swordfish in quick, savage rushes. Percy was becoming exhausted; his arms ached; his breath came short. He could not keep up the fight much longer. Where was the Barracouta?

He shouted at the top of his lungs. Unexpectedly, out of the fog to starboard Jim's voice answered him.

"Sharks!" yelled Percy. "This way! Quick!"

"Fight 'em off! We're coming!"

In less than two minutes the sloop was alongside, and oars and harpoon helped beat off the assailants while the prize was being hoisted aboard. Though badly gouged and bitten about the head, the swordfish was but little impaired in value, for its body had hardly been touched. Another of about the same size lay in the standing-room. It had been a good morning's work.

Percy told his story as the Barracouta nosed home through the fog. When he had finished, Jim dropped his hand on his shoulder.

"Perce," said he, "you certainly put up a great fight and saved your fish. Nobody could have done any better."

Those few words, Percy felt, amply repaid him for what he had gone through that morning. He had won his spurs and was at last a full-fledged member of Spurling & Company.