There was no mistaking that sharp, whip-like report. It was the crack of a revolver!

Breaking the silence at a time when they had felt certain that the nearest human being was miles away, the sound had a startling effect on the five boys. Not one but felt a thrill of apprehension, almost of dread. Who besides themselves was astir at so late an hour on that lonely island? Why? The weapon that produced the report must have been aimed at something. What? For a moment they remained silent, breathless.

Spang!

A second shot, distant but distinct, rang out from beyond the brow of the bank behind the cabin. Spurling sprang from his bunk.

"Boys!" he shouted. "Somebody's after those sheep! Turn out!"

Hurriedly he began dressing. The other four followed his example, fumbling with clumsy fingers in the darkness. Nemo gave a short, sharp bark.

"Quiet, boy!" ordered Jim; and the dog subsided, growling.

Percy experienced a peculiar shakiness; but he dressed with the others. Out here were no policemen or other officers to enforce the laws. Whatever was done they must do themselves.

Jim, his first excitement over, was cool as usual.

"All dressed, fellows?" he inquired, as calmly as if the pursuit of midnight thieves was a common incident.

Everybody was ready.

"Going to take the dog?" asked Throppy.

"No! Leave him here! He might bark when we didn't want him to."

"Here's the gun!" volunteered Lane.

"Don't want it! If we had it with us, we might lose our heads and shoot somebody. Whoever they are, they haven't the least idea there's any one on the island besides themselves. They've probably landed at the Sly Hole from some vessel that's approached the north shore since it came dark. Hungry for a little lamb or mutton! But those sheep have stood Uncle Tom a good many dollars and he can't afford to lose any of 'em. Where's that flash-light?"

"Here 'tis!" said Budge, passing him the electric lantern.

Jim snapped it quickly on and off again.

"Righto!" was his verdict. "All ready? Then come on! But first tie that dog to the stove-leg, so he won't bolt out the second we open the door."

Throppy fastened Nemo.

"Quiet now!" cautioned Jim.

He opened the door carefully, and the five filed out into damp, cool, midnight air.

Stars filled the sky. A gentle wind was blowing from the southwest. Nothing broke the stillness save the low murmur of the sea on the ledges. Without hesitation Jim led his party at a dog-trot eastward along the beach. When he reached the rocks he halted.

"We'll go straight across to the Sly Hole," he said. "I know a short cut through the woods. Either they've killed a sheep already and are carrying it down to their boat or they've frightened the animals so that it'll take some time to get near enough to 'em again to shoot. What sticks me is why they don't use a shot-gun instead of a revolver. Now, boys! Right up over the rocks!"

It was a rough climb, but soon they were on the top of the bluff. Unerringly Jim led them to the entrance of a narrow trail penetrating the scrubby growth.

"Look out for your eyes! Don't follow too close!"

The pliant, whipping branches emphasized his caution. By the time the party gained the north shore their hands and faces were badly scratched.

The little basin of the Sly Hole lay below. Looking down, they could make out a dark object at the water's edge.

"There's their boat!" whispered Jim. "They're still on the island."

Spang!

Another report from the pasture beyond the evergreens echoed emphatic confirmation to his statement. Jim took two steps toward the sound, then stopped.

"Not yet! I know a better way. Stay here and keep watch."

He scrambled down to the beach. There was a slight grating of gravel, and presently the boat was afloat. Noiselessly, under Spurling's skilful sculling, it slipped out of the cove and vanished behind the ledges to the east. Before long Jim was back with his companions.

"I've made their dory fast in a little gulch among the rockweed," said he. "They'd have a hard time to find it unless somebody told 'em where it is. They can't get away without having a reckoning with us."

Spang-spang-spang!

Three reports in quick succession. Jim laughed.

"Wasting a lot of cartridges! Must want that mutton pretty bad! Either they're awful poor shots or they've made the sheep so wild they can't get anywhere near 'em. There's their vessel!"

The boys' eyes followed his pointing finger. Not far offshore were the vague outlines of a schooner.

"All black!" said Jim. "Not a light of any sort! That looks bad. Besides being against the law, it shows there's some reason why they don't want to be recognized. I don't know what kind of scalawags we're up against, but we've got to be mighty careful."

Percy felt a strange sinking at the pit of his stomach. To be plunged into an encounter with a gang of unknown ruffians on his first night offshore was more than he had bargained for. For a minute Jim stood thinking.

"I'm almost sorry we didn't take that shot-gun!" he muttered. "No, I'm not, either! We might be tempted to use it, and that'd be worse than losing every sheep on the island. Hold on! I've got an idea."

The boys gathered closely round him.

"Listen!" he whispered. "Budge and I will go ahead through the woods to the pasture. You three follow close behind. If there's any shooting, throw yourselves flat. No use taking chances with such fellows as those!"

Crouching low, sometimes actually creeping, the party, Jim and Lane in the lead, made their way under the close boughs toward the open. Suddenly Jim sank to the ground. Warned by his whisper, the others did the same.

Footsteps were approaching. Then voices in heated argument reached their ears.

"Aw, come on, Cap!" expostulated one unseen speaker. "What's the use chasin' round over this pasture all night? Here we've wasted an hour already. I've fired away all my cartridges, and we haven't nailed a single bleater. We've got 'em so wild we can't sneak up within half a mile of 'em. Let's quit it for a bad job, go aboard, and turn in!"

"Cut it out, Dolph!" impatiently retorted another voice. "You've got a backbone like a rope! Guess if you were footing the grub bill aboard the Silicon you wouldn't be so fussy about being broken of your beauty sleep. I've paid out all the good dollars for stores that I intend to on this trip. You know we've plenty of ice aboard, and a couple of these sheep'll furnish enough fresh meat to last us to the Bay of Fundy and back. That ought to hit you in a tender spot. You're always the first man down at the table and the last to leave it."

"You needn't twit me on my appetite, Bart Brittler!" exclaimed the other, angrily. "If you weren't so stingy with the grub on board your old catamaran I wouldn't be hungry all the time. A man who makes as much money as you do, runnin' in—"

"Stop right there! You know there's some things that were never to be mentioned."

"What's the harm? There's nobody within miles!"

"That may be. But we can't be too careful in our business. Now what about the sheep?"

"I'll stop here half an hour longer. Then I'm goin' aboard."

"Well, I'll tell you what we'll do. You hide in the edge of the woods, and I'll make a circuit and drive 'em down to you. Here, take these cartridges and my revolver! That'll give you two to work with. You'll have to shoot quick when they come."

There was a sound of breaking branches. The boys flattened themselves on the carpet of needles as a man's body crashed toward them through the underbrush.

"All right!" announced Dolph. "I've found a good place, close to a sheep-path. Now drive down your mutton, and I'll butcher it as it goes by. Will two be enough?"

"Sure! And that's two more than I'm afraid you'll get, unless you shoot straighter than we've done so far to-night. It may be twenty minutes before they come, for I'm going to make a wide circle to the west, so as to get behind 'em."

The captain's footsteps died hollowly away on the turf and Dolph settled himself comfortably in his chosen ambush, almost within reach of Jim's hand. Five minutes of silence passed. Jim was debating what he should do. Budge lay close to him, and not far back were Throppy, Percy, and Filippo, hardly daring to breathe. Circumstances had placed one of the marauders so nearly within their grasp that a sudden, well-planned attack could hardly fail to make him their prisoner. But there must be no bungling. A man with two loaded revolvers, and desperate from panic, would be a dangerous customer unless he were overpowered at once.

It would not do to let too much time go by. Brittler would soon be returning, driving the sheep ahead of him; then they would have two lawless men to contend with, instead of one, unless they chose to be quiet and tamely allow the spoilers to make off with their booty.

Jim came to his decision like the snapping of the jaws of a steel trap.

Reaching back, he pressed Budge's hand, as a signal for him to be ready. Budge returned the pressure. Dolph stirred and drew a long breath. There was a moment of suspense. Overhead, a crow cawed harshly.

Noiselessly Jim rose to his hands and knees and crept forward. The small twigs and needles, crackling under his weight, sounded in his ears like exploding fireworks. He stopped; went on again; stopped; went on again. How could Dolph fail to hear him coming? The distance was less than two yards, but to the crawling lad it seemed far longer.

Now he was close behind the unconscious bandit. He straightened up, setting his right foot squarely on the ground. As he did so a little branch snapped. Dolph, startled, turned his head. Before he could lift a finger Jim was upon him like a panther.

There was an indistinct cry of alarm.

Spang!

Off went a revolver, discharged at random, and the two were struggling in a confused heap under the low boughs.

It was a short fight. A third figure launched itself into the mÊlÉe. Though not nearly so strong as Jim, Budge alone would have been a good match for any average man, and the two of them together speedily vanquished Dolph. A firm hand was pressed over his mouth and he was relieved of his automatics. Finding that his captors were not disposed to injure him, he soon ceased his struggles.

Silence again. One of the would-be plunderers and the weapons of both were in the boys' hands. What should they do next?

"Hi! Hi! Scat, you brutes! Get a move on!"

Brittler's voice shattered the midnight stillness as he came, driving the sheep before him. From their covert the boys could look across the pasture and see the black, leaping shapes fast drawing nearer. It was high time to prepare to meet their second foe.

"Throppy, Whittington, Filippo! Come here! Quick!"

They came, Percy in the rear, his knees shaking.

"Budge, can the four of you handle this man if I let go?"

"Easy!"

"Keep his mouth shut till I tell you he can open it!"

"All right!"

Lane's hand replaced Jim's over Dolph's lips. The other three grasped him wherever they could find a chance. It would not have taken much to shake off Percy's trembling grip, but the prisoner was content to remain quiet.

There was a patter of hoofs; the sheep were coming. Soon they were flitting by the ambush, shying off as their keen senses warned them of possible danger. Again they scattered toward the northwest end of the island. After them danced Brittler, roaring with anger.

"What are you waiting for, you numskull?" he cried. "Why didn't you shoot? I heard you fire once some minutes ago, and thought you might have been aiming at a stray one. I had almost the whole flock bunched right before me. You couldn't get a better chance if you waited a week. Now I've got to waste another half-hour chasing 'em round again. What's the matter with you, anyway? Why don't you speak?"

He was within five yards of the silent group under the spruces when Spurling's voice rang sharply out:

"Halt there!"

At the same instant he flashed the ray from his electric lantern straight into the captain's face.

Brittler stopped short, as if struck by lightning. His jaw dropped, and a ludicrous look of alarm and bewilderment overspread his features.

"Take your hand off his mouth, Budge," ordered Jim, "and let him tell the captain what's happened."

Thus adjured, Dolph spoke:

"I've been taken prisoner, Captain. They jumped on me in the dark and I had a chance to fire only one shot. I think there's at least half a dozen of 'em, and they've got both our revolvers, so we haven't a chance. That's all there is to it."

Brittler had recovered from his first panic. He bristled up with pretended indignation.

"What do you mean, whoever you are, by jumping on us this way? And take that light off my face! I don't like it."

Spurting did not remove the steady ray from the features of the irate captain. He waited a moment before replying.

"Captain Brittler," he said, "you and Dolph came to steal sheep, and it isn't your fault that you haven't been able to do it. You thought there was nobody on this island and that you could kill and take to suit yourselves. You've been caught red-handed. By good rights you ought to be turned over to the sheriff. We'll let you go this time, but if we catch you here on such an errand again you'll have a chance to tell your story before a jury."

"How'd you come to know my name?" blustered the captain. "I s'pose you've been pumping that mealy-mouthed landlubber of a Dolph."

"Dolph hasn't said a word till he spoke to you just now. He couldn't. I guess we understand each other, so you and he had better start for the Silicon. You'll find your dory in the rockweed about fifty feet east of the cove. I'll keep your revolvers a few days, and then mail them to you at the Rockland post-office. You can get 'em there. Better go now! Turn that man loose, Budge!"

Muttering vengeance, Dolph and the captain disappeared in the direction of the Sly Hole. After giving them ample time to find the dory, the boys quietly made their way to the north shore.

A boat with two men was visible, rowing out to the Silicon. As soon as it reached its destination the schooner got under way and proceeded eastward.

"I don't like the looks of that craft," said Spurling. "There's something suspicious about her. Did you hear what Dolph said to the captain about making money? They're engaged in some kind of smuggling, or I'll eat my hat! But what it can be I haven't any idea. Well, we're lucky to be rid of 'em so easily. Guess they'll give Tarpaulin Island a wide berth after this. And it's dollars to doughnuts the captain never inquires after those revolvers at the Rockland office. I didn't feel it was quite safe to give 'em back to him just now, but I didn't want to take 'em away for good. He can do as he pleases about sending for 'em."

He yawned.

"It's past one, and we'd better be getting back to camp, or we won't be in condition for our busy day to-morrow. Come on, boys!"

Slowly, and a trifle weariedly, the five made their way across the island. Even though the fire in the stove had gone out long since, the warmth of the cabin felt good to them.

"Well, Whittington," remarked Spurling as they once more crept into their bunks, "how do you like your first night on Tarpaulin? Some life out here, after all, eh?"

Percy had recovered his assurance. Now that the experience was over he rather enjoyed it.

"Not so bad," he replied.

Before he went to sleep he lay for some time thinking.