Richard Gregory stirred restlessly in his sleep vaguely aware of an unfamiliar sound, a faint tapping, insistent, disturbing. He wakened sharply and sat bolt upright, conscious of the fact that he was fully dressed. Then he remembered.

"All right, Bill," he called softly. "Coming."

It took but a minute to shove his automatic into his pocket and secure his rifle from the corner. Groping his way to the door he stood shivering on the threshold, staring into the thick gray fog which enveloped him.

A hand touched his shoulder. Strong fingers tightened on his arm.

"This way," a low voice directed. "Careful, don't scuff."

Gregory started to speak but a warning pressure of the big fingers restrained him. His companion led the way. He followed in silence. Through the winding streets of the little fishing village they went, the familiar landmarks about them looming grotesque and mystical in the low-hanging fog. At length the acrid air of the sea assailed their nostrils and the silence of the night was broken by the noisy splashing of a marsh-loon.

Bill Lang stopped suddenly. Faintly through the gray void came the muffled gulping of an under-water exhaust. Huddled together they stood listening. To Richard Gregory the sound indicated only the slow approach of a motor-boat. To the trained ear of the fisherman it meant that Mexican Joe was on time with the Sea Gull.

Lang led on down the loosely boarded wharf piled high with ill-smelling fish-boxes and paused at the head of a narrow gangway, looking back, listening. Close by the dock Gregory discerned the outline of a fishing-boat, magnified by the fog into whimsical proportions. Descending cautiously, he followed Lang aboard and groped his way into the protecting shelter of the engine-house. The cold mist clung to his flesh and he drew his coat closer about him. The soft breathing of the heavy-duty motor became more pronounced, more labored. The clutch was in. They were backing out into the stream. He glanced above him at the stay where the starboard side-lamp hung. But the grayness was unbroken by a single ray of green.

Lang was running dark.

It was taking a long chance on such a night as this, Gregory reflected. But then the whole business was a long chance. And Lang knew his business.

Imbued with a fisherman's sixth sense of feeling his way along familiar channels rendered unfamiliar by fog, Bill Lang piloted his craft skilfully down the silent bay in the direction of the open sea.

Crouching in the bow, Mexican Joe sought with cat-like eyes to pierce the gray veil of blinding fog. Narrowly averting collision with unlighted harbor-boats, bumping at times over sandy shoals, plowing through grass-grown mud-flats and skirting dangerous reefs with only the smallest margin of safety, they came at last to the jettied outlet of Crescent Bay.

The roar of the breakers sounded ominously close through the gray canopy of fog. The little craft rocked briskly in the trough of the swell as Lang threw the wheel over and headed out to sea. Flashing a small light over the compass, which served as an improvised binnacle, he peered intently at the instrument. Then he spoke softly to the man forward.

"Take the wheel, Joe."

When the Mexican had relieved him Lang bent low over the compass and examined his watch. Then he joined Gregory.

"Twelve o'clock," he announced. "We've got to make Diablo before daybreak. Sixty-five miles in less than four hours. That means hurry in weather like this."

He turned to the man at the wheel.

"Crowd her, Joe," he called. "We're taking chances to-night. If we hit anybody we might as well hit hard."

"Do you think we got out without being seen?"

Lang shook his head sagely in the darkness.

"Not much of a chance," he answered after a moment. "Couldn't have had a better night, though. But it's mighty hard to slip anything over on the dago. If the fog would lift up it would be even shootin' you'd see one of Mascola's outfit trailin' us astern. We've got him nervous, I tell you."

"It's high time they were getting nervous," Gregory rejoined. "When they try to browbeat American fishermen off the high seas and coastal waters it's time somebody was getting nervous."

He was silent for a moment and Lang as usual only grunted his assent. Then Gregory went on:

"But there's something else that's making them nervous, Lang. Something they are doing around that devil-island. What kinds of laws they're breaking out there nobody knows. They may be doing anything from shooting fish to catching chicken-halibut or baby barracuda. We don't know what. But we do know they're mighty touchy on who cruises round El Diablo. When our boats get around that infernal island something always happens. You know that."

Lang's grunt was emphatic and Gregory concluded:

"That's why it's up to us to find out what it is. It's hard enough to get the fish as it is without Mascola staking out the water like he owned it and telling us to keep out."

For some time the two men leaned together against the engine-house, each keeping his own counsel, each busied with his own thoughts. Then Gregory spoke:

"If anything happens to me to-night, Lang, keep all this business to yourself until my son comes home. Tell him. No one else. We want to get to the bottom of this thing ourselves without any one else butting in to bungle the job. Do you understand?"

When Lang had gone to relieve the Mexican at the wheel Richard Gregory's thoughts turned to his son overseas. Should he have waited until his return? He wondered. It was a young man's work, such a job as this,—and yet,—no, it was better to get to the bottom of the thing to-night. His head sank lower on his breast. Perhaps he could snatch a few winks of sleep. He might need it.

The muffled rattle of the anchor-chain caused him to waken sharply, stiff with cold. The motor was silent. The launch rocked lazily. Through a rift in the fog he saw a rocky beach only a stone's throw away. They were anchored close by the shore.

"Hell-Hole," announced Lang in a whisper.

Gregory picked up his rifle.

For a moment the big fisherman by his side hesitated. Then he said: "Why not stay on the Gull, Mr. Gregory? Let Joe go ashore with me."

"No."

The answer was decisive. There were no explanations. Lang knew it was final. Assisted by the Mexican, he swung the dory free and lowered it quietly into the water. Helping Gregory into the small boat he turned to the Mexican and spoke rapidly in Spanish. Gregory could catch only the substance of a few sentences. Lang was telling Joe to stand by for a quick get-away. To watch the beach and start the anchor when he saw them coming. And above all he was to keep quiet.

The bow of the dory grated on the beach. The two men stepped out and without a backward glance slowly disappeared into the fog.

Huddled in the bow, Mexican Joe waited by the anchor-chain, his eyes searching the little cove. For a long time he sat thus, not even daring to light a cigarette. Once his straining ears caught the muffled exhaust of a motor-launch. It came very close but the fog guarded him well and he heard it pass on. What the two men were doing upon the island concerned Mexican Joe not at all. The devil-isle was filled with secrets. Why should he try to fathom them? He was paid to obey and SeÑor Lang had twice saved his life.

A sound from the shore caused Joe to struggle to his feet and begin hauling on the chain. Then he looked again, stopped and straightened up.

There were three men coming along the beach, four,—five.

Joe dropped behind the rail and watched them climb over the rocks and halt by the empty dory. Then he heard the sound of low voices in a foreign tongue, and shivered. The voices of the men on the beach grew fainter. They were minutely examining the dory. One lifted his arm and pointed seaward in the direction of the Sea Gull.

The Mexican crept to his sawed-off shotgun loaded with buck-shot. Securing the weapon he made his way again to the bow and waited. The rock-bound cove was silent. The dory was still on the beach. But the men were gone.

At length came the rattle of loose stones mingled with the sound of low-pitched voices. Gracious a Dios. It was SeÑor Lang and SeÑor Gregory. Joe's hand leaped to the anchor-chain. There would be need to hurry. He tugged hard at the heavy cable, then he stopped, straightened and screamed a warning.

Gregory and Lang whirled about only a few feet from the dory. From the shadowed crevices in the rocks, men leaped forward and hurled themselves to the beach. About the skiff bright jets of flame cut the fog. Came the sharp report of an automatic, twice,—three times.

Mexican Joe watched the unequal struggle, huddled against the rail. His eyes brightened with fear. Twice he raised his gun, but his hand shook. At the distance the shot would scatter. There would be no use. He saw the two men fight their way to the dory. Saw Lang reach it, shove it into the water. The SeÑor was safe. Gracious a Dios. But no, he was going back for SeÑor Gregory. Sangre de Christo, they would all be killed.

The fog thickened. The struggling forms merged, grotesquely intermingled and became indistinct. From behind the gray curtain came the sound of heavy blows, muttered imprecations, groans.

Joe waited for the veil to lift, staring with straining eyes, cursing softly. Los SeÑores were being murdered before his eyes and he could do nothing. Through a rift in the fog he saw Gregory with his back to the cliff fighting back the savage horde which were pressing hard upon him. He was using his rifle as a club. The men were falling away from him. Lang had cleared the way to the skiff; was almost at his companion's side.

From the overhanging ledge above, two dark figures leaped suddenly upon the man beneath, wrenching his gun from his hand, crushing him to the sand. Lang fell upon the group of struggling figures, fighting like a madman. Then he staggered, dropped to his knees and went down before the onslaught.

Again the gray pall drifted down from the tall crags above and blotted out the scene.

Joe staggered to his feet, grasping the wire-stays for support. Then he stiffened and stood listening. The muffled purr of a high-powered motor disturbed the silence. From out the gloom to starboard he saw the bow of a big motor-boat cut the fog. The Mexican shrieked a warning and tightened his clutch on the stays.

The strange craft veered, the sharp bow swung over. With wide-open engines, she struck the Sea Gull amidships, full on the beam. Hurled to the deck by the impact the Mexican heard the snapping and grinding of timbers. He was conscious of falling and the cool rush of waters about his head. Then he remembered no more.

Wrapped in a clinging mantle of filmy fog, rock-bound, grim and mysterious, the Island of El Diablo frowned at the sea from behind the veil of silence. Brave men had sought to fathom her secret but she had guarded it well.