On the floor above, Professor Folcroft Urlich still held The Shadow's agents captive. While the master of
darkness remained below, the master of silent death was planning the doom of The Shadow's aids.
Who held the balance: Professor Urlich or The Shadow? Were their cross-purposes to meet before the
victims died?
The scales of fate were trembling, while master minds prepared their methods.
CHAPTER XX. CARDONA ENTERS
WHILE strange events were occurring on Long Island, Larry Ricordo was making all haste toward
Manhattan. The gang lord, fleeing town at Professor Urlich's request, had neared his destination. He was
mounting the steps from the East Side subway at Forty-second Street.
As a natural procedure, Larry Ricordo turned up Lexington Avenue to enter the Grand Central Station
from the east. It was scarcely later than half past twelve. Plenty of time remained to catch the Chicago
Limited.
Larry Ricordo seldom liked haste when it was unnecessary. As he moved leisurely through the midnight
crowd along the avenue, his lips twisted scornfully. Even if the police were out to capture him, they stood
little chance of getting him now.
Nevertheless, Larry Ricordo fondled the revolver in his coat pocket. One challenging word: the
challenger would get the works. This was the attitude that the gang leader held as he entered the wide
passage from the street.
Larry's eyes were keen and cautious. Even in this thronged entrance, the gang lord did not trust entirely
to his inconspicuous appearance. He prided himself upon his watchfulness. His boast to Professor Urlich
was still strongly in mind.
The crowd spread as it reached the huge central concourse. Larry Ricordo, as he walked across the
great expanse of floor toward a ticket window, was no longer one of a large throng. He was in the open
— a single figure that could easily be spotted by watching eyes.
A man swung from the wall and walked swiftly after the gang leader. Larry Ricordo was not aware of the
man's approach until the stranger was close beside him. It was then that Larry turned to recognize a face
that seemed familiar.
The man made a sudden leap upon the gang lord. That action meant more than recognition. Larry
Ricordo knew his assailant for a detective. Wresting free, Ricordo whipped his big revolver from his
pocket.
Another man had sprung up behind the gang leader. The second detective made a quick grab for
Ricordo's arm. Larry fired once, his shot aimed upward as a hand seized his wrist. The detectives were
flashing their own guns. Two more men were springing to their rescue.
Shouts of men; screams of women — these were heard as people scattered for shelter.
LARRY RICORDO'S revolver roared again. A detective went down with a bullet in his shoulder. The
others struggled ferociously. They were trying to get their man alive, to prevent gunfire in this open space,
where hundreds of people stood in danger of stray shots.
But Larry Ricordo was a fiend who balked all capture. He sent one detective sprawling on the floor;
another after him. One of the downed men fired upward and missed. Larry, an evil snarl on his lips,
dropped the fourth, who still struggled with him.
Spinning across the floor of the concourse, the murderous gang leader leaped to meet a fifth, who
blocked his path. He swung his huge revolver to deliver a death shot. This time the gang lord failed.
The last antagonist did not falter. His revolver was in his hand, and before Larry could shoot to kill, this
detective fired point-blank into Ricordo's body.
The gang leader staggered on; a second shot, delivered coolly at close range, sent him sprawling to the
floor.
Rolling upon his back, clutching at his wounded side, Larry Ricordo saw the face of Joe Cardona above
him. The ace detective had stepped in where the others had failed. It was the swarthy sleuth who had
finally felled Larry Ricordo.
With futile clutch, Ricordo grasped for his revolver, which had fallen beside him. True to his boast, the
gang leader intended to go out fighting. His weakening fingers fumbled; a moment later, Cardona had
kicked the weapon out of reach.
dropped. Through it all, Joe Cardona never desisted from a purpose which had steadfastly filled his mind
for the past half hour.
There was a reason why he had sought to capture Larry Ricordo alive, rather than dead.
"Ricordo!" Cardona was staring squarely into the gang lord's face. "Ricordo! Who's the guy in back of
this!"
Ricordo coughed. Blood appeared upon his lips. An evil leer followed the crimson. Coughing, gasping,
Larry Ricordo spat defiant words at his questioner.
"Try — try to find out!" he challenged, in a broken snarl. "Try to — to make me squeal. You — you got
me — but that's all!"
Cardona pressed back those who were crowding around. He knew that Ricordo was dying. In the last
minutes of life, the gang lord would have to talk. Cardona, acting on a hunch, played his final trump.
"You know why we got you?" he demanded. "I'll tell you why! We were tipped off that you were taking
the Chicago Limited. Tipped off half an hour ago. We want the bird who gave the tip-off. Do you know
him?"
Ricordo's eyes were glassy. Now they opened wide.
On the verge of death, the gang lord forgot his wounds, forgot his enmity toward the police. All that he
could sense was the tone of Joe Cardona's words — cold utterances that sounded plainly amid the
muffled murmur of the concourse.
LARRY RICORDO forgot the excited cries about him. He could hear only Cardona's voice, repeating
the same theme in steady demand:
"We were tipped off. We want to know just where the tip-off came from."
"I'll tell you where!" coughed Ricordo. "I'll tell you where! It came from the guy in back of this game!"
In a spasm of dying fury, the gang leader had gained a tremendous hatred for the man who had betrayed
him. Bewildering thoughts were racking Ricordo's brain. Only one man could have played the traitor.
That man was Professor Folcroft Urlich.
Why not? The scientist had brutally disposed of Thomas Jocelyn. Similarly, he had decided to get rid of
Larry Ricordo. To go out fighting — all because of a double-crosser! With failing strength, Ricordo gave
the answer that Joe Cardona wanted.
"Urlich!" gasped the gang leader. "Professor — Folcroft Urlich! Place — on Long Island. Go — there.
He — he is — the one — "
"He tipped us off?" questioned Cardona.
"He — he must have," blurted Ricordo. "He — he told me to scram. Get him— out on Long Island — place
called Philbrook — "
Cardona was nodding. He saw Larry Ricordo close his eyes. The gang leader gasped no longer. But his
dying brain responded suddenly to a wild thought. A tremor shook Ricordo's frame as he remembered
the death trap which Urlich had prepared for all comers.
"Cardona" — Larry's lips snarled as his eyes opened for the final effort. "Look out — when — you
get — when — you get — "
The effort was too great. Ricordo's twisted lips spat out a dying sigh. The gang leader's body nearly
rolled from Cardona's grasp. The detective could feel it go limp. He knew that the final spasm had
arriv
ed. Larry Ricordo was dead!
Cardona let others hold the body. He arose to see Mayhew close beside him. Quickly, Cardona ordered
the other detective to take charge of Ricordo's removal. A dozen sleuths were here. Cardona growled
orders.
Two minutes later, the ace detective was striding from the terminal with a squad of men at his heels. They
piled into a waiting car, and Cardona gave the driver quick, tense orders. The car shot from the curb.
Shrieking along Lexington Avenue, it turned eastward toward a mammoth bridge that led to Long Island.
Detective Joe Cardona had worked speedily to-night. Less than an hour after Thomas Jocelyn's death,
he had received the tip-off concerning Larry Ricordo. Half an hour later, the gang lord had spoken
before he died from Cardona's shots. Half an hour from now, Cardona and his men would be at their
new objective.
Joe Cardona was on the trail of silent death. He did not know that one had gone before him — that The
Shadow was already at the spot where such death lurked.
The ace detective was pleased because he had forced those words from Larry Ricordo's dying lips. He
did not know that the gang lord had tried to give a warning also, but had failed!
Cardona and his men were heading for a fiendish trap. Soon they were to know the power of silent death
that Folcroft Urlich wielded!
CHAPTER XXI. TUBES OF DOOM
IN Professor Urlich's laboratory, a fiendish plan was nearing its completion. Cliff Marsland and Clyde
Burke, still bound beside the wall, were watching preparations that they knew would mean their doom.
All the lights in use within the room had been concentrated on this side of the laboratory, which was near
the front of the building. Sanoja and Rasch, the scientist's willing servants, had fitted gleaming
incandescents with reflectors so that a vivid glare pervaded this limited field.
Professor Urlich was seated in a folding armchair, with the air of a director in charge of a rehearsal. His
orders, barked in foreign tongues that the attendants understood, had brought forth prompt obedience.
Yet the forthcoming experiment had required considerable time for preparation.
Cliff Marsland had ceased to feign grogginess. Clyde Burke, beside him, was also fully conscious.
Despite the cold terror which Professor Urlich's presence caused, both of The Shadow's agents were
strangely fascinated by the details of the work which now seemed completed.
Directly in front of the two men stood a huge tripod, mounted on a circular base. This was a skeleton
structure that ran on wheels, and its three legs gave it the grotesque appearance of a lonely gallows. At
the top of the tripod were extended arms that supported a rim of metal.
This upper circle supported a huge carboy. The glass vessel, incased in wickerwork, gleamed with
greenish hue. Its stopper, which had been inserted in place, was a glass plug from which extended two
flexible pieces of shining hose.
As Sanoja pressed a little lever beside the rim that supported the carboy, the large container rocked
slightly, showing that it was on a pivot that would enable it to be inverted. Sanoja readjusted the lever
and the big vessel ceased to sway.
On either side of the central tripod stood a low skeleton base with upright rods that terminated in rings.
There were two of these, both large and massive.
Each pedestal held a container of thick glass, shaped like a mammoth test tube. Neither of the prisoners
had ever before seen such tremendous cylinders of glass. The tubes were more than eight feet in height,
and more than two feet in diameter.
As final preparation, Urlich's men had brought forward two caps of metal large enough to fit over the
large tubes. They had attached a hose to each cap. Professor Urlich cackled joyously as a signal that
everything was ready.
CLIFF MARSLAND studied the face of the fiend. A demoniacal glee illuminated Urlich's features. The
scientist had watched the work of his servants with increasing interest.
In spite of that fact, Cliff had noticed that the professor never failed to note the three unlighted
incandescents that projected above the spiral stairway at the center of the laboratory. Those bulbs were
scarcely visible in the darkness beyond the concentrated illumination; but had one suddenly commenced
to gleam, the professor would have spied it on the instant.
"We are ready, now," remarked Professor Urlich, his eyes focused upon the silent prisoners. "Inasmuch
as you are to be the subjects of my experiment, I shall explain its operation to you."
He beckoned to Rasch, who appeared with a small tube that contained a tiny white mouse. The servant,
a grin on his dull face, held the tube in the light. The prisoners noted that it was capped with a metal cover
that had a round hole in the center.
Professor Urlich babbled in a foreign language. Sanoja passed a glass bottle to Rasch. The man held the
tube in one hand, the bottle in the other, and poured a greenish fluid from bottle into tube.
A sizzling, smoky mixture manifested itself. The green was tinged with white and fumes slowly came from
the hole in the cover. Slowly, the liquid cleared.
Simultaneous gasps of amazement came from Cliff and Clyde. The white mouse had vanished. The tube
contained nothing but a watery fluid!
"It has always been my wish," proceeded the professor, "to attempt this experiment on a larger scale. The
greenish fluid which you observed — the same liquid which is in the large carboy — is virtually a universal
solvent. It has no effect upon glass; but that is about the only substance which it does not dissolve with
rapacious power.
"The pieces of hose which project from the carboy are my own invention — a flexible material which
possess certain properties found in glass. It has been used to withstand the power of the solvent.
"Perhaps it is unkind" — Urlich's eyes were gleaming with irony— "to discuss the details of this experiment
with my subjects. Perhaps you would prefer to be as the white mouse was: ignorant of what is to come.
However, I have already given you a very complete inkling, so I may as well proceed.
"Your lives mean nothing to me. Your deaths, however, would be advisable. In order to leave no
evidence of my experiment, I find it most convenient to destroy you as I have done with the mouse.
"These large test tubes were made for such an experiment as this. One tube for each of you. After that,
we shall attach these lengths of hose, invert the carboy and let the solvent do its work."
CLYDE BURKE chewed his lips. Cliff Marsland stared steadily ahead. Each man realized now the
fiendishness of Professor Urlich's cunning, scheming mind. More horrible death could scarcely be
imagined. To be dissolved, while totally helpless, within a mammoth tube of glass!
Both of The Shadow's agents could feel the terrible sensation of that vitriolic fluid that was to come!
Professor Urlich cackled wickedly. He saw the consternation on the faces of his intended victims. He
was joyed by the thought of the swift, silent death that was to be theirs.
Even more did he relish the cunningness of his scheme. To reduce these living men to nothing but a slimy
sediment; then to pour out the remains that could leave no vestige of a clew to the crime that he had
perpetrated!
This was death supreme; crime raised to the level of scientific achievement. Professor Urlich had no
; desire to question his victims. Let them call out for mercy if they would; babble secrets of The Shadow. If
their words seemed important, the experiment could be delayed. If not, it would go on.
The Shadow meant little to Professor Urlich now. The very fact that he held one — possibly two — of The
Shadow's agents in his power meant that The Shadow must have died from the fumes of Thomas
Jocelyn's sighing death.
Clyde Burke was staring hopelessly at the merciless countenance of the professor. Cliff Marsland was
looking beyond, toward the distant rear of the laboratory. His eyes blinked suddenly. Had he seen a
motion by what appeared to be a doorway? Had he seen a barrier open; then close?
Was it imagination, or did Cliff catch a glimpse of a moving form that glided along the hazy wall, unseen
by any of the others present? The thought, at least, offered a ray of hope.
Cliff heard a nervous gasp from the man beside him. He spoke in an undertone, without moving his lips:
"Steady, Clyde. Steady. Stick it out, old man."
The reporter nodded. The test tubes were swinging forward, on swivels from the tripod pedestals.
Professor Urlich's servants approached and lifted Cliff Marsland.
The Shadow's agent offered no resistance. His body slid into the tube; it swiveled upright, and Cliff could
see the attendants going to get Clyde Burke. Helpless, he watched them slide the reporter into the other
tube.
BOTH containers were upright now. Professor Urlich and his minions seemed grotesque shapes through
the curved walls of the tube. Clyde Burke, inspired by Cliff's bravery, was staring at them also. Professor
Urlich was pointing toward the caps.
Suddenly, the scientist stopped. He was staring upward toward the row of lights above the central
stairway. The red incandescent had become suddenly illuminated.
Some one was within the outer zone of death — the portico that surrounded the circular building!
Harsh orders burst from the professor's lips. Sanoja and Rasch nodded as each caught the message
intended for him. They were to proceed with the experiment. Their master had other work to do.
Hastily, Professor Urlich crossed the laboratory, and opened the door that led to the hollow cylinder.
Rasch brought forward a ladder and mounted it. He stood beside Cliff's tube and motioned to Sanoja to