Harry remembered what Marquette had told him about that experimental room, below the level of the
lake. It was the only outlet from the cellar. Arlette must be down there.
Without a moment's hesitation, Harry descended the steps.
He came upon a huge metal door, located on a landing; the door was opened toward him. Beyond it
were more steps, that led into a small, stonewalled room.
Harry's flashlight showed a mechanical device opposite the steps— presumably the torpedo tube. Then
he saw the torpedoes themselves, standing against the wall—heavy, metal shells, more than six feet in
length.
Now his light revealed something on the floor. There lay Arlette, pitifully helpless—bound and gagged.
Harry drew his revolver, and rushed down the stone steps. He flashed the light in every direction.
There was no one else in the room. The man who had captured Arlette had gone.
Harry quickly cut the cords that bound the girl. He released the gag. Arlette had fainted; now she revived
and tried to speak. Harry watched her lips; then saw that they framed a warning.
'Look out!' was her feeble exclamation. 'He is here!'
A SOUND came from above, up by the stone stairs. Harry swung his flashlight in that direction, and
leveled his revolver. The gleam of the light revealed the form of a man—a man who wore a brilliant red
mask across his face.
The roar of Harry's revolver was cannonlike in the little room; but his shots were too late.
Just as his finger sought the trigger, Harry saw a crimson-clad hand against the edge of the metal door.
The huge barrier swung shut; the bullets from Harry's gun were deflected by the sheet of steel.
'He was behind the door,' gasped Arlette. 'I saw him there, Harry.'
The door was not entirely shut. Harry noted a width of a few inches. He dashed for the steps; but as he
approached, the muzzle of a revolver was pressed through the opening.
The red hand that clutched it pressed the trigger. Harry collapsed as the bullet struck his shoulder. He
tripped from the steps, rolled over, and lay motionless upon the stone floor.
A few seconds passed; then the door was pressed shut from the other side. A loud click followed, as an
automatic lock was fastened.
Arlette turned to Harry. The man groaned, as she pressed a handkerchief against his wound. His head
had struck the floor, and he had been momentarily stunned. He recovered his senses, and looked about
him.
'We are trapped,' said Arlette. 'But perhaps we may escape. Some one may -'
She stopped, her attention attracted by a sound in the room. She looked toward the wall, away from the
stairs.
Two sluice gates had opened, one on each side of the torpedo tube. Water was pouring into the room.
The girl knew that she and her companion were doomed. From the cellar above, the Red Envoy had
released the switch that controlled the sluices. Harry and Arlette were helpless, in the midst of an
increasing flood that was sweeping in from the lake.
CHAPTER XXVIII. MASTER MINDS MEET
ON this particular night, a strange effect came over the professor within a few minutes after he had taken
his medicine.
Harry Vincent had scarcely left the room, when the white-haired old man began to gasp. Then he leaned
forward upon the desk. His eyes closed, and he was still.
The door opened, and a figure entered. It came with amazing silence, and Professor Whitburn would not
have observed it, had his eyes been open.
The Shadow leaned over Professor Whitburn. He pressed the old man's forehead; then felt his pulse.
The old inventor was not dead; he was simply the victim of a powerful opiate. The wrong pills had been
left on his desk by Marsh; and the action had been performed with the definite purpose of rendering
Professor Whitburn unconscious.
The Shadow moved away from the desk, and stood motionless. He was a strange figure, this mysterious
man, as he stood there.
His broad-brimmed hat was pulled low, and his cloak obscured the lower part of his face. Only his eyes
showed from the dark depths that hid his features.
Those eyes were searching. They looked keenly in every direction, as though trying to discover some
secret of the professor's study. They were looking for a hiding place; and they sought it in some unusual
location.
They stopped upon a bookcase. There were several shelves in the bookcase, and above them was a
thick molding that ran the entire length. It was ornamented with carved sections.
The Shadow stepped to the bookcase, and ran his hand along the molding. His hands appeared for the
first time; they were thin, well-formed hands, with sensitive fingers that moved as though filled with a life
of their own.
The fingers stopped on one spot; they pressed; then moved to the left. A portion of the molding went
inward, and slid beneath the next section. The opening showed a strip of metal, with a tiny keyhole.
The Shadow went back to the desk. He carefully raised the old professor, and leaned him back in his
chair.
The hands of The Shadow found the professor's watch chain. There were keys on one end; but none of
the keys were suited to the little lock. The Shadow removed the professor's watch.
Now the black-cloaked man became suddenly intent. He was holding the watch in his right hand. His left
was poised above.
THE SHADOW was listening. His keen ears had caught a slight sound. His left hand moved beneath his
cloak. Then it reappeared, and held a peculiar position, the fingers slightly apart. The right hand skillfully
removed the watch from the chain, and laid it on the desk.
The Shadow stepped back, his eyes still intent upon the professor. He turned toward the door, and as he
did, the door swung inward noiselessly.
A man stood there; a man whose face was obscured by a crimson mask. His hands wore red gloves; and
one of them held a leveled automatic.
'Hands up!' came the command from the door.
The Shadow slowly raised his arms. He had apparently been caught unawares. The eyes beneath the
mask were watching the figure in black; but they also seemed to look beyond; for they saw the opened
molding of the bookcase.
'Do you know me?' questioned the masked man, in a harsh, sarcastic voice.
The Shadow did not reply.
'I am the Red Envoy,' said the man with the crimson mask. 'You did not expect me.'
Still no reply.
'So you are The Shadow?' The Red Envoy's tones carried bitter irony. 'The Shadow—whose identity
no one knows. I see that you have aided me.
'One of my agents told me to-night that he suspected the bookcase as the hiding place of Professor
Whitburn's papers; but he had not located the exact spot. I must thank you for your work.'
The masked man inclined his head in a short, quick bow. Still The Shadow was silent and unmoving, both
his hands raised, slightly forward.
'A key is needed,' said the Red Envoy. 'Where is it?' Receiving no reply, he added:
