That was why he had allowed himself to fall so easy a victim to the attack of a exhausted man.

His quick efforts revived Marsland. Grim words spurted into Cliff's ear.

The cold bite of the water roused Cliff still further, as he followed TheShadow into the lake. The Shadow swam in a different direction from the one that the fleeing Mason had taken. The mainland at this point was quite close.

Marsland kept grimly behind the bobbing head of The Shadow. A soaked arm drew him safely to sh.o.r.e. The two stepped through slippery mud to the rutted road that circled the lake. They could hear from the other side of the island the faint echo of the outboard motor.

Marsland followed the flying heels of The Shadow. They raced along the lake road, hidden by the screen of trees.

But Rodney Mason beat them. When they rounded the last curve in the wooded road and could see again the level waters of the lake, the boat in which Mason had fled was jammed nose-deep into the bank.

Footprints led into the thicket where The Shadow had left the sedan containing Sam Baron and Squint. Baron's car was gone!

The Shadow did not echo Cliff Marsland's gasp of dismay. His eyes were ablaze with a grim flame. He had expected something like this. He had tested Mason as a man tests an unknown element in a chemical experiment. Mason had reacted positively.

The answer seemed incredulous. Why should Rodney Mason attack the rescuers who had saved him from torture at the hands of Baron's gang? And why should he flee with his kidnapers?

There were two possible answers to the riddle. Either might be true.

Perhaps Mason trusted no one; perhaps he suspected that The Shadow and Marsland were members of a rival underworld gang, as much to be feared by him as Sam Baron's mob.

But the second theory was a more sinister one. Not for an instant had The Shadow allowed himself to forget that behind Baron's gang was an unknown master criminal who pulled the strings. Not even Baron himself knew who that chief was.

By an overzealous mistake, Baron might have kidnapped his own chief!

The Shadow was by no means sure of this. But there was grim laughter in his throat, as he stared at the empty thicket where Baron's sedan had stood.

CHAPTER XII.

WHO IS OTTO MULLER?.

WHEN Rodney Mason's stolen beat rammed its nose upward on the muddy edge of the mainland, his eyes gleamed shrewdly. He knew that the blows that had dropped Marsland and The Shadow had been hurriedly dealt. Mason had been almost exhausted when he had swung his treacherous gun b.u.t.t. He was aware that pursuit would not be long delayed.

Mason dived through the concealing branches, to where he remembered the sedan had been parked. Its front wheels pointed toward the road.

With Turk's gun steady in his grasp, Mason flung open the rear door. He studied the unconscious faces of Baron and Squint. Both were tied securely; both were gagged.

Mason chuckled with the air of a man contemplating a very pleasant joke.

He slammed the rear door. Circling the car, he slid coolly behind the wheel and started the motor. He had worked so swiftly that barely a minute had elapsed since he had leaped ash.o.r.e from the boat.

Nosing out of the thicket, Mason sent the sedan speeding along the road.

As he neared the foot of the steep hill, he increased the speed recklessly.But the fleeing chemist was an excellent driver. He reached the top of the hill without accident. He took the winding lane back to the main highway.

When he felt the smoothness of concrete under his humming tires, Rodney Mason laughed with high-pitched delight at his escape.

The highway led straight southward to New York. Presently, Mason reached a busy Westchester County intersection. He turned, approached the New York City limits through Yonkers. The chemist's goal was the subway line that ends at Van Cortlandt Park. He wanted to get rid of Baron's car, for the subway was a safer bet for a smart man.

Driving into the park, Mason took one of the broad, winding roads. His speed slackened. Presently, he saw what he wanted - a narrow lane that branched off toward a more secluded section of the huge park. He followed the lane to a spot that was utterly deserted except for the gray, flitting shapes of a couple of squirrels.

The frightened squirrels vanished. So did Rodney Mason.

THE moment he had the sedan parked out of sight, Mason yanked open the rear door. A quick tug of his hand lifted the lap robe from the unconscious crooks.

He searched them with swift efficiency. He found nothing on Squint but a gun, a box of cartridges, and a thick wad of currency.

But the eager chemist made a more interesting discovery on the crumpled figure of Sam Baron. He drew a folded sc.r.a.p of paper from an inner compartment of Baron's wallet. The paper was dirty and creased, but the typewritten words on it were clearly legible.

It was a note signed by a man whose name made Mason's eyebrows lift with quick interest. He read: The ice business is picking up. Get the ice wagon ready. But no smoke wagon unless you have to! Same split as usual.

OTTO MULLER.

Mason shoved the note into his pocket. His eyes were pin points of cold flame. He knew that in the underworld argot, "ice" meant jewelry. A "smoke-wagon" was a gun. The note was an obvious order to Sam Baron to pull a jewelry robbery without gunplay or noise.

But the name signed to that strange message was not so obvious. Who was Otto Muller? Mason made note of the license number of the sedan. There was a chance that the car was registered in Baron's name; but Mason had a queer hunch that it wasn't. He intended to make sure.

He didn't return to the lane along which he had driven in the sedan. He pushed across the park on foot, taking a short-cut through the shrubbery, till he emerged on a pedestrian path.

Five minutes later, Mason was out of the park, hurrying to the steps of the subway station.

He took an express downtown, went straight to the Motor Vehicle Bureau.

After a little trouble, Mason had the information he wanted. The sedan was registered in the name of Otto Muller. His address was listed as a business number on the upper west side of the city in Washington Heights.

Rodney Mason's tight smile deepened as he left the building. He decided to investigate the Washington Heights address at once. But another thought stayedhim.

He thought of a girl. A gorgeous, slim-figured blonde on Park Avenue, who might make trouble for a smart man unless she was properly handled. Rodney Mason whistled for a taxicab. He gave the driver the address of Isabel Pyne.

ISABEL flushed when she saw Mason. She was wearing a silken house coat that emphasized the curved perfection of her figure. She swayed eagerly toward Mason. He slid an arm about her soft, ungirdled waist.

Then Isabel caught her breath and recoiled. She noticed that the maid whom she had hired to help her pack her belongings, was still in the room.

Mason glanced keenly at the maid and the half-packed suitcases on the floor. He masked his quick frown with a smile.

"What in the world is going on Isabel? You're not moving, are you?"

"Yes. I - I decided I wanted to get away for a while. I telephoned for maid service to help me pack. That's all there is to it, Rodney."

"I see." His smiling lips brushed her car, whispered, "Get rid of the maid!"

Isabel looked puzzled, but she obeyed. When they were alone, Mason caught Isabel to him. He crushed her in a quick embrace.

"Do you love me?" he whispered in her ear.

Her body relaxed in his arms. Mason bent and kissed the ivory gleam of her tilted throat. When he released her, Isabel laughed shakily. Her tremulous hand tightened the loose house coat across her bosom.

"Why are you moving?" Mason asked her.

"I'm frightened! You - you know what happened to me last night."

"That's why I came here to see you," Mason replied in a low voice. "I've got a place picked out where you can live in perfect safety."

Isabel shook her head.

"It won't be necessary. I'm planning to stay at the home of my uncle, Julius Hankey. He's been begging me to visit him for a long time."

Mason tried to dissuade Isabel from her purpose. He was so stubborn and insistent that at last the girl began to grow angry. There was a queer look in Mason's smiling eyes, that revived Isabel's suspicion of his behavior on the preceding night. She reminded him of his peculiar absence from home. She asked him flatly where he had been.

Rodney dodged a reply. Isabel was unable to pin him down. Smilingly, he agreed that the home of Julius Hankey was probably the safest place for her to stay. To stop further talk about his own activities, he told her of his discovery that a man named Otto Muller was leagued with the crooks who had stolen his sapphires.

Fright returned to Isabel's eyes. She begged Rodney to notify the police.

Either that, or to drop the whole thing and mind his own business.

Mason drew her closer to him. Isabel's heart began to pound dizzily. She was conscious of his warmth and his strength. Then sanity returned to her.

Gently, she pushed him away, her bosom heaving under the thin silk of the house coat.

"Rodney, you must go! This - this is madness!"

She laid a timid hand on his arm.

"Promise me that you won't - won't mix yourself up any further with this man Muller! You're risking death!"

"I promise," Rodney Mason told her.

BUT Mason was lying. He had no intention of dropping the trail his shrewdness had already uncovered. The moment he left the Park Avenue apartmentof Isabel Pyne, he called a taxicab and drove swiftly northward to Washington Heights.

He didn't give the driver the address of Otto Muller. He had already consulted a city directory. He knew the street corner that was nearest to the number he was seeking. When he left the cab, his eyes peered eagerly down the avenue.

Dusk was falling. The sidewalk was a blaze of lighted shop windows and electric signs. There was one sign, midway down the block, that made Rodney Mason's heart leap. It was a neon sign in bright red letters. The sign threw a reflection on the sidewalk like a crimson smear of blood. It read: OTTO MULLER.

Delicatessen and Table Luxuries Mason was so interested in the sign that he saw nothing else. He was unaware of the casual glance he received from a man who was lounging under a cigar store awning at the corner. The man held a folded tabloid newspaper in his hand. He kept idly tapping his thigh with the paper.

He had seen Mason alight from the taxicab. He had watched his quick glance toward the delicatessen. He waited, tapping his leg with the paper.

But as Mason started to walk slowly along the sidewalk, the man who was watching him changed his position. He stepped out toward the curb. The rolled newspaper lifted toward the brim of his hat. He gave the hat a quick upward shove, as though it had settled too low on his forehead. Having done this, he vanished around the corner.

A workman in stained yellow dungarees saw that innocent-looking signal.

He was standing near another workman, close to the curb. A manhole cover had been lifted, and the two laborers seemed to be busy with pails, ladder and rope gear. But there was no metal guard railing about the open manhole in the pavement.

As Rodney Mason approached the spot, one of the workmen blundered into his path. He apologized as Mason b.u.mped into him. Then, suddenly, he thrust out his foot and shoved.

The broad back of the second workman shielded the first. Mason fell staggering forward, his arms outflung to save himself. His feet skidded on the greasy rim of the open manhole.

He plunged straight downward with a shrill cry.

His yell drew instant attention to the accident. People turned, just in time to see the unfortunate chemist vanish into the open manhole. Women screamed. Men shouted and ran forward.

The two workmen handled the confusion deftly. One of them seized the ladder and slid it downward through the manhole. The other drove back the crowd with a grim shout.

"Take it easy, folks! Get back! The guy'll be all right! We'll have him out in a jiffy!"

His companion vanished nimbly down the ladder. He had picked up a small wrench, but n.o.body in the crowd noticed that minor detail. Nor could they see him after his head dipped below the surface of the pavement.

MASON, floundering on hands and knees at the slimy bottom of the pit, heard a panting breath. Looking over his shoulder, he saw his a.s.sailant swing the wrench with silent fury. It cracked against Mason's skull. He dropped in a sodden, unconscious heap.

He was instantly picked up by the man who had slugged him. Hanging like alimp sack over the workman's shoulder, he was carried up the ladder to the street.

"Better call an ambulance," the man with the wrench said to his partner.

"The poor guy hit his head when he fell. He's hurt!"

"I did call an ambulance - Hey, get back, everybody! Here it comes now!"

It was extraordinary that an ambulance could respond to an accident call with such speed. But n.o.body in the excited crowd thought of that. The clanging of the bell made the crowd squeeze forward. A white-coated intern shoved through the throng and made a quick examination.

"The man's skull is fractured," he said, and motioned toward the ambulance.

The driver brought a stretcher. Mason was slid swiftly into the ambulance.

The chauffeur ran to his seat, and the white-coated intern squatted jauntily in the rear.

The ambulance sped away. It was marked "HOSPITAL" in large neat letters.

The paint looked exceedingly fresh.

The two workmen closed the manhole with a bang of the metal cover. They gathered up rope, ladder and pails. Turning the corner where the man with the folded newspaper had vanished, they hurried to a small truck at the curb. The chauffeur of the truck was the man with the newspaper.

Both workmen sprang aboard. The truck sped down the dark side street.

"See any cops?" the driver growled in a hard, metallic voice One of the men in dungarees chuckled.

"Not a one! Boy, when we work, we work fast!"

Onlookers on the avenue began to scatter. The only spectator who knew anything about the truth was a quiet man who stood on the outskirts of the crowd, panting a little. He had arrived a moment or two before the ambulance.

He had recognized the faces of the driver and the intern. Smart guys, both of them! A neat s.n.a.t.c.h job!

He was Sam Baron. His report, phoned in from a telephone pay station just outside Van Cordlandt Park, was responsible for the whole kidnap scheme.