DEAR MISS DODGE:

This weapon shoots exactly into the center of the light disc. Keep it by you.--A FRIEND.

"Let me see it," I asked, taking the gun. Sure enough, along the barrel was a peculiar tube. "A searchlight gun," I exclaimed, puzzled, though still my suspicions were not entirely at rest. "Suppose it's sighted wrong," I could not help considering. "It might be a plant to save some one from being shot."

"That's easily settled," returned Elaine. "Let's try it."

"Oh, mercy no,--not here," remonstrated Aunt Josephine.

"Why not--down cellar?" persisted Elaine. "It can't hurt anything there."

"I think it would be a good plan," I agreed, "just to make sure that it is all right."

Accordingly we three went down cellar. There, Elaine found the light switch and turned it. Eagerly I hunted about for a mark. There, in some rubbish that had not yet been carted away, was a small china plate. I set it up on a small shelf across the room and took the gun. But Elaine playfully wrenched it from my hand.

"No," she insisted, "it was sent to me. Let me try it first."

Reluctantly I consented.

"Switch off the light, Walter, please," she directed, standing a few paces from the plate.

I did so. In the darkness Elaine pointed the gun and pulled a little ratchet. Instantly a spot of light showed on the wall. She moved the revolver and the spot of light moved with it. As it rested on a little decorative figure in the center of the plate, she pulled the trigger.

The gun exploded with a report, deafening, in the confined cellar.

I switched on the light and we ran forward. There was the plate--smashed into a hundred bits. The bullet had struck exactly in the centre of the little bull's-eye of light.

"Splendid," cried Elaine enthusiastically, as we looked at each other in surprise.

Though none of us guessed it, half an hour before, in the seclusion of his yacht, Woodward's friend, Professor Arnold, had been standing with the long barrelled gun in his hand, adjusting the tube which ran beneath the barrel.

In one hand he held the gun; in the other was a piece of paper. As he brought the paper before the muzzle and pressed a ratchet by gripping the revolver handle, a distinct light appeared on the paper, thrown out from the tube under the barrel.

Having adjusted the tube and sighted it, Arnold wrote a hasty note on another piece of paper and inserted it into the barrel of the gun, with the end sticking out just a bit. Then he wrapped the whole thing up in a box, rang a bell, and handed the package to a servant with explicit instructions as to its delivery to the right person and only to that person.

Down in the submarine harbor, Del Mar was in conference with his board of strategy and advice, laying the plan for the attack on America.

"Ever since we have been at work," he remarked, "Elaine Dodge has been busy hindering and frustrating us. That girl must go!"

Before him, on the table, he placed a square package. "It must stop,"

he added ominously, tapping the package.

"But how?" asked one of the men. "We've done our best."

"This is a bomb," replied Del Mar, continuing to tap the package. "When our man--let me see, X had better do it,--arrives, have him look in the secret cavern by the landing-place. There I will leave it. I want him to put it in her house to-night."

He handed the bomb to one of his men who took it gingerly. Then with a few more words of admonition, he took up his diving helmet and left the headquarters, followed by the man.

Several minutes later, Del Mar, alone, emerged from the water just outside the submarine harbor and took off his helmet.

He made his way over the rocks, carrying the bomb, until he came to a little fissure in the rocks, like a cavern. There he hid the bomb carefully. Still carrying the helmet, he hurried along until he came to the cave entrance that led to the secret pa.s.sage to the panel in his bungalow library. Up through the secret pa.s.sage he went, reaching the panel and opening it by a spring.

In the library Del Mar changed his wet clothes and hid them, then set to work on an acc.u.mulation of papers on his desk.

That afternoon, Elaine decided to go for a little ride through the country in her runabout.

As she started to leave her room, dressed for the trip, it was as though a premonition of danger came to her. She paused, then turned back and took from the drawer the searchlight gun which had been sent to her. She slipped it into the pocket of her skirt and went out.

Off she drove at a fast clip, thoroughly enjoying the ride until, near a bend in the road, as it swept down toward the sh.o.r.e, she stopped and got out, attracted by some wild flowers. They grew in such profusion that it seemed no time before she had a bunch of them. On she wandered, down to the rocks, watching the restless waters of the Sound. Finally she found herself walking alone along the sh.o.r.e, one arm full of flowers, while with her free hand she amused herself by skimming flat stones over the water.

As she turned to pick up one, her eye caught something in the rocks and she stared at it. There in a crevice, as though it had been hidden, was a strange square package. She reached down and picked it up. What could it be?

While she was examining it, back of her, another of those strange be-helmeted figures came up out of the water. It watched her for an instant, then sank back into the water again.

Elaine, holding the package in her hand, walked up the sh.o.r.e, oblivious to the strange eye that had been fixed on her.

"I must show this to Lieutenant Woodward," she said to herself.

In the car she placed the package, then jumped in herself carefully and started off.

A moment after she had gone, the diver reappeared, looking about cautiously. This time the coast was clear and he came all the way out, taking off his helmet and placed it in the secret hiding-place which Del Mar and his men used. Then, with another glance, now of anger, in the direction of Elaine, he hurried up the sh.o.r.e.

Meanwhile, as fast as her light runabout would carry her, Elaine whizzed over to Fort Dale.

As she entered the grounds, the sentry saluted her, though that part of the formalities of admission was purely perfunctory, for every one at the Fort knew her now.

"Is Lieutenant Woodward in?" she inquired.

"Yes ma'am," returned the sentry. "I will send for him."

A corporal appeared and took a message for her to Woodward. It was only a few minutes before Lieutenant Woodward himself appeared.

"What is the trouble, Miss Dodge?" he asked solicitously, noting the look on her face.

"I don't know what it is," she replied dubiously. "I've found something among the rocks. Perhaps it is a bomb."

Woodward looked at the package, studying it. "Professor Arnold is investigating this affair for us," he remarked. "Perhaps you'd better take the package to him on his yacht. I'm sorry I can't go with you, but just now I'm on duty."

"That's a good idea," she agreed. "Only I'm sorry you can't go along with me."

She started up the car and drove off as Woodward turned back to the Fort with a lingering look.

Del Mar was hard at work in the library when, suddenly, he heard a sound at the panel. He reached over and pressed a b.u.t.ton on his desk, and the panel opened. Through it came the diver still wearing his dripping suit and carrying the weird helmet under his arm.

"That Dodge girl has crossed us again!" he exclaimed excitedly.

"How?" demanded Del Mar, with an oath.