Diablo was steeped in moonlight. For miles about the sea gleamed like a mirror. The grim mountains which guarded the shore were robed in saffron and checkered with black by the dark shadows of the towering peaks as they fell athwart the hillsides and mingled with the darkness which hugged the canyons.

From a small cave high up on a rocky canyon wall the figure of a man emerged and crept silently into the shadows. Picking his way with great caution along a winding sheep-trail, he reached the summit of the hill and looked about. The damp sea air fanned his long hair and caused him to look in the direction of the fleecy white clouds which were creeping upward from the horizon. Soon there would be fog. Then he could continue on his way to the brackish spring on the bluff-side overlooking the south shore. From there it was only a stone's throw to the beach where the mussels and abalones clung so thickly to the rocks.

The thought of the raw shellfish sickened him. For days he had had nothing else to eat. Shrinking closer into the shadows of the sage and cactus, he waited for the fog. Then he could go on on his nightly journey. How many months had he been a prisoner on El Diablo? He had lost all track of time. But what did it matter? Soon he would be dead. For warm food and a drink of pure water he would almost give himself up now.

Borne on the fog-wind came cries and shouts from the other side of the island. Perhaps help was coming at last. But no, it was only the fishermen fighting among themselves off the Hell-Hole. He had heard them many times before across the narrow isthmus. They would only go away as they had always done and leave him to starve. The faint pulsing of a motor launch directed his attention to the sea.

In the paling moonlight, a gray blot clouded the water, moved slowly among the rocks and merged with the shadows. It was the same boat he had seen so often in the past. Always it came to the island at night, running dark. Once in the bright moonlight he had seen men land on the rocks and walk up the beach to a large cave which extended far into the cliff. As he had huddled closer into the scant shadows of the rock-mottled ledge, other men had come down the trail from the island and he had been forced to slide into the chilling waters of a grass-grown pool to escape detection. Mother of God, it had been a narrow escape.

The fog thickened and he continued on his way to the spring. Creeping noiselessly through the brush he reached the trail which led downward to the beach. Then he stopped and listened. The soft grating of a muted chain caused him to drop lower in the grass and draw back. Silently he retraced his steps until he reached the cover of the heavier brush which fringed the hillside.

The strange vessel was dropping anchor again in the little cove. He dared not run the risk of going farther down the trail. There were mussels and abalones around the next point. He would get them. By that time perhaps the men would be gone and he could return by the spring. The fog settled close about him, blinding his eyes and clinging to his shivering body. For a moment he stopped and sucked thirstily at the wet grass. Then he crawled on.

Planing high on the glistening waves, the Richard sped onward across the moonlit sea in the direction of El Diablo. At the wheel, Kenneth Gregory strove to concentrate his mind upon the quest which lay before him. But another thought obtruded with ever recurring frequency. Why had he permitted Dickie Lang to accompany the party to the island? There would be danger. There was always danger at El Diablo. Landing upon the island would be an added risk if Hawkins' suspicions had any grounds for fact. The girl's threat that she would withdraw her support from the cannery if not permitted to go with the expedition, was only a bluff: Why had he not remained firm? He knew the answer. There was a look in the girl's eyes which he could not withstand. Something in her voice which left him powerless to refuse as she had said:

"Our fathers were not afraid. They died in one boat to learn Diablo's secret. We've fought together from the start. Don't leave me at the finish." She might have added: "If they get you, they might as well get me too."

But her eyes told him that. Well, it was too late now to change his mind. The girl was here and it was up to him to leave her in a place of safety if such could be found upon the island. While Hawkins conferred with his two friends, Gregory laid his plans.

He would leave Dickie with the Richard. She had her automatic and a rifle. They would lay in close to shore on the south shore, opposite the Hell-Hole. The island was narrowest there and it was generally in that vicinity that things had happened oftenest in the past. That was where the Gray Ghost put in, the place too where his father and Bill Lang had met their death. With the fishing fleet fighting Mascola's boats on the north side the opposite shore of the island might not be held in such rigid surveillance.

His thoughts turned again to the girl by his side. The rock-shadowed coves would afford a fair anchorage for the Richard, even on such a night as this. There Dickie could see without being seen. Should danger threaten while the landing party were ashore, she must put to sea. He must make that perfectly clear to her at once.

As he expected, he encountered stubborn resistance from Dickie Lang. If there was anything to be found out, she wanted to be there to see it. She was not afraid. She could shoot as well as a bunch of newspapermen. What was the idea of leaving her clear out of it? Gregory smiled at her slurring reference to Hawkins' two friends. Then he reflected that what the girl did not know concerning the real object of the mission to Diablo would cause her no worry. Until the party landed at least, he was in command of the expedition. And orders must be obeyed.

"You'll have to do as I say," he concluded. "Whether you like it or not."

Dickie's lip curled and she turned her head away to hide her face. "All right," she answered. "I'll stay on the Richard." To herself, she added: "But I'll use my own judgment when it comes to running away."

In the silence of the fog the prisoner of El Diablo crept warily on. Deep ravines laced his path and yawned close about the trail. A misstep would hurl him to the bottom of the rock-lined gorge which was swallowed up in the mists at his feet. Suddenly he stopped and threw himself to full length on the ground. Far above him the solid whiteness of the fog wall was broken by irregular flashes of blue. To his ears came the sound of snapping spluttering flames.

Covering his head with his arms, he crossed himself. The devil was speaking from the hilltop. On two other occasions he had heard the crackling of the flames near the old sheep-herder's shack on the crest of the hill. He had taken the wrong trail. Had gone too far. Worming his way down the path he fled from the flashes of blue light.

For some time he retraced his steps in silence, thanking his saints that the devil had spoken to warn him from the spot. Then the soft breathing of a motor-launch caused him to stop and listen. He was again at the bluff-side. Soon he would reach the rocks. The echoes of the motor-boat died suddenly away and he groped his way to the edge of the cliff and scrambled down the trail.

"You'd better take her now. The fog's getting pretty thick and I don't know the shore-line along here."

Dickie Lang took the wheel.

"I don't know it any too well myself," she admitted. "We'll have to go mighty slow and feel our way along."

Throttling to quarter-speed they skirted the south shore of the island and nosed their way along the coast. At length the girl suggested a halt.

"We ought to be nearly up to the Hell-Hole Isthmus by now," she whispered. "On the beach along here there should be a lot of tide-water caves if we're where I think. Around the next point is the goose-neck. We'd better go ashore and have a look. We may be too far down already."

Gregory agreed.

"I'll take Hawkins and Slade and row ashore," he said. "Billings can stay with you on the launch."

Dickie's objections were quickly overruled and the canvas-wrapped anchor chain was lowered into the water while the dory was pulled alongside.

"Look along the base of the cliff for the caves," cautioned the girl in a low voice. "And watch out for your oars. Keep them in the water and be sure the wrappings fit tight in the locks."

Gregory nodded and took his place in the skiff.

"We'll be back in five minutes," he said. Then he shoved the dory out into the fog.

From the ledge of rock which bordered the cove, the half-starved man pulled the razor-backed mussels from the sea-grass and broke them open with his pocket-knife. For some time he ate rapidly. Then he ceased pulling at the shellfish and listened. A boat was coming to anchor in the cove. He could hear the soft slip of the chain through the chaulks. Perhaps they would land on the beach. Then he would be trapped on the ledge until they had gone.

Picking his way over the barnacled rocks he started for the beach. As he climbed from the ledge, he stopped suddenly and clung to the rocks. On the beach at his feet, and only a few feet away, he heard the pebbles grate beneath the bow of a boat. The men were already landing. Staring into the opaque wall of white, he saw it clouded by three dark blots. Followed the rattle of stones, the soft crunch of the sand dying slowly away into silence. The men had gone on up the beach.

The man who clung to the rocks climbed noiselessly to the sand, his brain burning with one great idea. While the visitors were gone from the place he would steal their boat. In the fog no one could find him. He could row about the island and be picked up at sea in the morning by some fishing-boat. The great chance had come to him at last.

Perhaps the men had left another to guard the boat. The thought caused him to draw his pocket-knife. Grasping it tightly in his shaking fingers, he crawled silently over the wet sand, feeling for the sides of the dory with his extended arm.

Hope danced brightly before his eyes as he touched the boat. Weakened by hunger, he rubbed his shriveled limbs and tottered to his feet, waving his knife. Then he chuckled aloud. There was no one in the boat.

Throwing the knife upon one of the seats, he leaped again to the sand and began to shove. Mother of God, he had no strength. The bottom grated noisily on the pebbles. Then the dory slid into the water. Laughing to himself, he threw his body over the rail and felt about for the oars.

Men were running down the beach. He had not a second to lose. His hand closed upon the oars. He was saved. Tugging feebly at the heavy sweeps, he drew them through the water with all his might and the dory moved slowly forward. Again his weakened muscles responded to the fevered call of his brain. Suddenly he felt the dory strike a heavy object ahead. Thrown half from his seat by the impact he dropped an oar, regained it on the instant and pushed the skiff away from the launch as hands reached out to grasp it. Then he heard the low murmur of voices from the motor-boat. As he headed close in to the rocks he felt the stern of the dory dip sharply.

Gregory whirled at the sharp rattle of oars and raced down the beach in the direction of the dory. Some one was meddling with their boat. When he reached the place where they had left the skiff, he found it gone. From the waters of the little cove came the creak of oar-locks. Plunging into the water, Gregory swam rapidly in the direction of the launch. Whoever had taken the boat was heading straight for the Richard.

A sharp bump sounded close ahead and Gregory redoubled his efforts to reach the side of the launch. Then he narrowly escaped being run down by the small boat which had turned and was heading in for the rocks. Grasping the stern of the dory as it moved by him, he hung for a moment while he regained his wind, striving vainly to ascertain how many passengers the skiff carried.

Suddenly he noticed that the oars no longer disturbed the water and the skiff had lost its way. Then he heard the sound of shuffling footsteps coming toward the stern. Releasing his hold, he swam along the side and caught the bow, dragged his body from the water and tumbled into the boat. The same instant a heavy oar crashed against the seat close to his head and a dark figure flung itself upon him.

It was but the work of a moment for Gregory to overpower the thief of the small boat and bind him with the dory's painter. The man had fought desperately only for a moment, then collapsed, and gibbering with fear had allowed himself to be bound without a struggle.

Turning the skiff about, Gregory started for the launch. Had the man landed others on the Richard? Surely he had reached the speed-boat and had put about. Was he bent only upon stealing the boat or was he only one of many who would be down upon them any minute?

Arriving alongside the Richard Dickie hailed him softly.

"Some fellow tried to steal our boat," he explained to the girl. "If you'll get Billings to help me get him aboard I'll go back and pick up the boys."

Dickie's companion in the launch assisted him in lifting the prisoner to the Richard's darkened cockpit where he lay huddled in a heap.

As Gregory rowed away in the direction of the shore, Billings veiled an electric torch and allowed its tiny ray to fall full upon the face of the quivering prisoner.

"A greaser," he whispered to the girl. "Look. He's scared to death."

Dickie looked quickly at the crumpled little figure. Then she fell on her knees close beside the man and peered intently into his shriveled face. For an instant she remained motionless staring into the face of the trembling captive.

"My God!" she whispered. "It's Mexican Joe."