This was the tank the Light had been wearing the night he had tried to cremate the dangling body of Harry Vincent in New Jersey!

THE SHADOW used his time to grim advantage. He was turning to retreat back to the secret elevator, when he suddenly halted.

He had heard a faint groan. The groan came from behind a bookcase filled with technical volumes.

Patiently, The Shadow worked at the shelves, after removing most of the books. He was rewarded finally by seeing the hinged barrier swing open.

He stepped into a short corridor that ran parallel to the rear of the bookcases. In front of him were three closed doors. The groan The Shadow had heard came from the door on the left.

He opened it. It was a small dungeon. A bound man lay writhing feebly on the stone floor. He had rolled on his face from weakness. The Shadow gently turned him over.

It was Clyde Burke.

Stepping swiftly back into the little corridor behind the cells, The Shadow opened the other two doors. In each he saw a helpless prisoner. His eyes glowed like flame. But he didn't release these two men. All he did was to lay a black-gloved finger across his lips, counseling quiet. He glided back to the cell on the left and released Clyde Burke. Into the dazed hand of his agent he slipped a businesslike .45. His lips moved in an almost soundless whisper.

Clyde nodded at the orders he heard. The Shadow examined the inner wall of the cell. A small piece of metal was visible on the smooth wall. It was shaped like an eyelid. The Shadow moved it aside and peered through a peephole.

He was staring into the room into which Clyde had plunged headlong through a trapdoor. The Shadow could see every detail of the chamber because it was now brilliantly lighted.

There was no sign of the Light. But there was something visible at the outer wall of the room that made the throat of The Shadow tighten. He guessed what the Light intended for Clyde Burke--and for The Shadow.

The thing looked like the shining breech of a cannon. But The Shadow knew enough about ordnance weapons to recognize the difference. Compressed air fired it, not gunpowder. It resembled a torpedo tube. The breech was large enough to admit the body of a human being.

A device to shoot living men like projectiles! But to where? And why?

The Shadow realized the answer, but he stifled his horror and anger. Intelligence was more important than emotion. With a warning gesture to his freed agent, The Shadow retreated swiftly the way he had arrived. He darted noiselessly back to the secret elevator, and ascended to the master bedroom.

Five minutes later, he was on the dark ground outside the house. He was ready now to enter the baited trap of the Light!

He descended into the circular pit where Clyde Burke had rashly gone. He rose, as Clyde had, into a dimly lighted reception room. His eyes picked out the armchair from which Clyde had been catapulted into the room below. He was able to do this unerringly as soon as he saw Clyde's hat. The hat was perched on the top of a tall cabinet behind the armchair. It had been placed at the edge so that The Shadow couldn't fail to see it.

The natural thing to do would have been for The Shadow to climb on the chair in order to examine the hat for a clue to his missing agent. But The Shadow did nothing of the kind.

He tossed a heavy weight--a dictionary from the bookcase--on the seat of the chair.

Instantly, hidden bands clamped over the chair arms. For a moment, nothing else happened. Then, without warning, the chair tilted forward. The bands on the padded arms opened. So did the floor in front of the chair, revealing a square black hole.

The Shadow leaped feet-first into darkness!

He landed without harm. But his m.u.f.fled cry indicated otherwise. It was a cry of agony. The Shadow threw himself flat to the stone floor. He lay in a tangled huddle.

Suddenly, a brilliant lamp glowed. A man was revealed. A tall man whose face was oddly blurred.

THE SHADOW blinked, unable to recognize that grease-smeared, double-face of the Light. It was more than double; it was triple, quadruple. Many faces in one, all strangely alike, yet all different.

A chemical illusion--but it didn't fool The Shadow. He had not wasted his time in the laboratory of the Light. He knew the secrets that had been stolen by a criminal genius from the murdered Crane Worthington.

The Shadow pretended agony. His leg was doubled under his sprawled body. It looked remarkably like a broken leg.

The Light spat ugly laughter.

"Welcome to The Shadow! I expected you."

He leaned forward. The concealed tank on his back gave him the look of a hunchback.

"You see the breech of that gun? It shoots human beings. Living ones! It shoots them under the water of the lagoon that I so carefully enclosed with stone breakwaters. Do you know there are sharks under that water? Hungry sharks, because they haven't been fed lately!"

The Light's voice was like a crooning of death.

"Do you mind if I slash you with a knife before I place you in the gun? Blood, you know. Sharks are fascinated by the smell of fresh blood. It maddens them, especially when they're hungry. You shall see!

"We'll experiment first with the living body of your agent. Then you'll know what to look forward to. I have a gla.s.s observation window that will give you a marvelous underwater view of the proceedings."

Groaning, The Shadow pretended to writhe feebly on the floor. The Light snarled evil laughter. He strode to the cell door behind which he had imprisoned Clyde Burke, flung it open with an arrogant gesture.

Clyde Burke stepped out behind the level barrel of a .45!

The Light screamed an oath of surprise. He leaped backward. His forefinger lifted, pointing viciously toward Clyde. But nothing happened. There wasn't even a pale moonbeam from that murderously pointing finger. The Shadow had removed the sting from the supreme weapon of the Light!

The Shadow was on his feet now, behind the trapped master criminal. He advanced calmly. Clyde didn't shoot. He had been warned not to by The Shadow.

His obedience almost cost Clyde his life. The Light sprang at him like a thunderbolt. Clyde was ready for battle, but he found himself over-matched by a criminal genius crazed with fear. The gun was wrenched from Clyde's hand. Its muzzle jerked upward in line with his stomach. Thrown headlong backward, Clyde was unable to save himself.

The Shadow saved him! The roar of the Light's gun was wasted. The heavy .45 slug rebounded harmlessly from a metal wall.

A furious battle began between The Shadow and the crime master. It was over almost as soon as it began. The Shadow took no chances. He was ruthless in his attack.

It was the turn of the Light now to lie on the floor in a moaning huddle. He no longer had the stolen .45.

His leg was twisted horribly. There was no fake about that broken leg. It was a compound fracture.

Clyde Burke stared at the helpless prisoner with mingled puzzlement and loathing.

"Who?" he gasped. "Trevor? Bascom?"

The sibilant laughter of The Shadow expressed amus.e.m.e.nt. He shook his head. Another name came from his lips. It was a name that made Clyde look astounded.

"George Stoker!"

'"But--" Clyde gasped.

"Wait!"

The Shadow whirled. He approached the two dungeon cells that adjoined the one where Clyde had been held. From each of them he dragged out a man. He slashed their bonds, helped them to their dazed feet.

One of the prisoners was Peter Bascom! The other was Carl Trevor!

The Shadow bent over the Light, wiped away the smear of chemical ointment that covered the criminal's face. The stuff glowed with a faint phosph.o.r.escence on the handkerchief The Shadow used.

But Clyde wasn't looking at the handkerchief. He was staring at the unblurred, clearly revealed face of Flash Snark's ex-lawyer.

IN a calm voice, The Shadow made many things clear. He spoke to Bascom and to Trevor, as well as to Clyde Burke.

The Shadow had known that George Stoker was the Light ever since the murder of Dawn Reed. The circles and squares and stars scrawled on the dusty lid of the mailbox had not been a code message.

They had been put there unconsciously by the nervous finger of the Light.

There was a word for that nervous scrawling habit. The cop at police headquarters had called it "doodling." Only one suspect in the case had the habit. George Stoker had "doodled" all over the place while he had waited in an anteroom to confer with Inspector Cardona! Stoker had faked his own kidnapping in order to avert suspicion away from himself if something went wrong at the last moment. He had callously allowed his bodyguard to be killed by mobster guns in order to make the s.n.a.t.c.h look real. His tale of the "warning message" to leave town was a cunning lie.

Stoker had killed Crane Worthington after he learned the secret of the inventor's ray--which was a highly concentrated form of gas combinations furnishing intensive heat far greater than any of the industrial torches could furnish.

Worthington had come to him for financial backing because the torch idea, as he had developed it, was too costly for commercial use, and needed more research. Stoker took it as it was and used it for his criminal purpose.

As a criminal lawyer, Stoker had perfect knowledge of underworld affairs. He decided to prey on big criminals, using the power of the ray. He was aware of the enormously valuable secondary rackets that had been built up secretly by Flash Snark and Tony Bedloe and other criminal chieftains.

Snark and the others had fallen victims because they were willing to take a short jail rap for the sake of keeping their secondary hidden. They didn't realize that it was the very thing the Light was after!

The Shadow stared at the two suspects he had saved from a horrible death. His face was grim. To Peter Bascom, he intoned a single word: "Why?"

The wealthy promoter shuddered. He looked shrunken and pale.

"I was crazy in love with Dawn Reed," he admitted faintly. "I didn't know she was the secret wife of Tony Bedloe. I thought she was in some sort of a jam with Trevor. When she disappeared, I suspected Trevor. I suspected that Carl Trevor might be the Light. I trailed him to the island. Tonight, I made a secret landing from my speedboat--"

His voice trailed off.

The Shadow turned to Trevor. There was understanding in his calm eyes, as he queried: "You suspected Dawn's murder?"

"Right after she took the plane for Rio," Trevor confessed. "I knew that the girl who boarded that plane was a fake. I thought Bascom had pulled some criminal stunt. I knew Dawn was afraid of Bascom, but I didn't know it was because she was scared that Bascom might get wise to her marriage with Tony Bedloe. I kept an eye on Bascom. I followed him out here to this horrible island!"

Making no comment, The Shadow switched his glance to Clyde Burke. The reporter for the Daily Cla.s.sic understood the unspoken order. It meant: "Telephone police."

The Shadow faded toward the laboratory where the inventive genius of Crane Worthington had been diverted to criminal ends by George Stoker. Police would find ample evidence there to end the career of the Light forever!

A challenge of evil had been conquered. The time had come for The Shadow to vanish into darkness. He would remain invisible until some fresh challenge to the law brought him back. THE END