'Vincent,' he said, 'you would have been dead this minute, if I hadn't been watching you. Perhaps you do
not know what this place is all about—but I suspect that The Shadow knows more than you.
'I am going to rely on you. I need your help. The Shadow saved my life once, and nabbed a bunch of
counterfeiters for me. I believe he is on the square. I'm going to chance it.'
He rose from his chair, and looked at Harry steadily. Then he asked:
'Those things that you saw last night—in the darkness above the house. Tell me. What did they look
like?'
'Ghosts,' admitted Harry.
The secret-service agent chuckled.
'They were aerial torpedoes,' he said. 'The results of Professor Whitburn's long experiments.'
'But they shone like phantoms -'
'Of course. Listen, Vincent. Professor Whitburn has made a remarkable contribution to scientific
warfare. His aerial torpedoes are under perfect control.
'Last night, he sent them out from the big machines in the corners of the tower. They were ejected shortly
after nine o'clock -'
'That's why the static came in on the radio!' exclaimed Harry.
'Of course,' replied Marquette. 'The torpedoes are under electrical control. Then they came back.
'The little lights were set to twinkle so that they could be observed from the tower. Then, when they were
near by, they shone, for they are coated with a luminous paint, so we can observe their approach.'
'But what came out of the lake?'
'I was responsible for that,' said Marquette. 'The professor believes that he can invent a torpedo which
may be shot from a submarine, yet which will take to flight when it reaches the surface of the water.
'There is a torpedo tube beneath the house—in a room deep in the basement. I was there. When I
received his signal, I shot the torpedo through an under-water cave, out into the lake.
'It rose, but failed to soar. The professor was watching from the tower.'
THE eerie events of the preceding night were now clear. But Marquette had further explanations.
'I shall start at the beginning,' he said. 'Much has happened here. Originally, Professor Whitburn
believed that he could revolutionize modern warfare by the invention of an aerial torpedo. He interested a
man named Jonathan Graham.'
'Graham is dead,' said Harry.
'What? How?'
'Suicide, it is said. He fell from his office window.'
'That looks bad,' remarked the secret-service man. 'When did it happen?'
After a moment's thought, Harry gave the approximate date.
'Hm-m-m,' said Marquette. 'So that's why Stokes lost the newspapers, two days in a row. Whitburn
may have learned it by letter - but I didn't know about it.
'But we can discuss that some other time. Let me tell the important story.
'Graham made Whitburn financially independent. The professor took this place. The secret service
learned what was going on—in part. I found out the rest.
'When I obtained a job here, Whitburn had one helper—a man named Blades. Then Stokes came along.
'Each one of us has different experimental work, and duties to perform. None of us could learn enough
to be of value.
'If Whitburn has drawings—which seems likely—he makes them himself, and stows them away
somewhere.
'Just as the torpedo was developing well, Blades was killed. A fly-wheel came off a machine which he
was using in the cellar workshop.
'I wondered about it at the time. But the coroner called the death accidental. I had tipped off the secret
service to stop any proceedings; but they never began.
'Marsh had been hired just before the death of Blades. That left three of us. A number of men applied; a
fellow named Barrows got the vacant job. He was killed, too. He was working in a room where we keep
chemicals.
'He made a mixture that formed a poison gas. It struck me as funny that he made the mistake he did; and
I couldn't figure why he didn't get out the door in time.
'Then I had my experience. The old motor boat sank in the middle of the lake. Started to fill as I got
away from the point of the island; I didn't see it until it was too late.
'I had told the professor that I couldn't swim, but didn't mind running the boat. I meant that I was a poor
swimmer—not that I was totally incapable. I managed to paddle the half mile to shore; the longest swim I
ever made in my life.'
'Whew!' exclaimed Harry, as Marquette paused. 'Looks like some one is out to get all of us. Who's the
man—Stokes?'
'Yes.'
'What about Marsh. Has he run into trouble?'
'Marsh,' replied Marquette, 'is a different case. I think that Stokes has reached him. I believe that the
object of these murders is twofold.
'First, to dispose of those who are not plotting against Whitburn; second, to install substitutes who are
confederates of Stokes.
'Marsh may be one of them. If not, Stokes has worked on him, and has gained his cooperation.'
'Then my job was to have been taken by some other person?'
'That's it, Vincent. But Professor Whitburn preferred your application to that of the man who was to
work with Stokes. I haven't been able to look at the list of applicants. That's the trouble, here. I can't
cross the old man.
'As soon as you arrived, I knew that you had a purpose. I doubted that you were the man Stokes
wanted. But I was afraid to reveal my hand until I was sure. Stokes must have known that you were
looking at the tower last night because -'
'Marsh saw me inspecting it this morning,' said Harry.
'Ah! That explains it. Where did you go to-night?'
'To meet a man in the village,' said Harry. 'I wanted to send a report to The—to headquarters.'
'To The Shadow.' Marquette supplied the name that had been upon Harry's lips. 'Perhaps Stokes
followed you. He did not come back here.'
'I suspect that he followed me.'
'Whether or not he saw the man you met,' said Marquette, 'he at least decided that you were playing
some game of your own. That necessitated immediate action.
'When I came upstairs to-night, I noticed that the tower door was ajar. So I watched from my own
room. Stokes sneaked up into the tower. He came down after a while -'
'He was tapping up there! That's the noise I heard. Trying to attract my attention.'
'I heard nothing in my room; but Stokes went up again, and came down immediately. Five minutes went
