As she crouched there trembling, her hand touched something cold--her skate. Here was hope; if the worst came to worst, here was a formidable weapon and she was possessed of the power to swing it.

Cautiously she drew it from her belt, then crouching low, gripping the small end, she waited.

Came again the pit-pat-pit-pat. He was on the balcony, she felt sure of that now. Her hand gripped the skate until the blade cut through the skin, but still she crouched there waiting.

When Florence failed to return, Marian and Lucile might have been seen pacing the floor while Marian pretended to study and made a failure of it.

"I think we should go out and look for her," said Lucile.

"Probably just a bit overcome by the wonderful skating in the moonlight,"

answered Marian, in what was intended as an unworried tone, "but we'll go down to the lagoon and have a look."

"Wait just a moment," said Lucile as she disappeared inside her laboratory. When she returned, something beneath her coat bulged, but Marian did not ask her what it might be.

After dropping down the rope ladder they hurried along the beach and across the park to the lagoon. From the ridge above it they could see the greater part of the lagoon's surface. Not a single moving figure darkened its surface. For fully five minutes they stood there, looking, listening.

Then Marian led the way to the edge of the ice.

By the side of a clump of bushes she had spied something.

"What's that?"

"Pair of men's rubbers," replied Lucile kicking at them.

For a full moment the two stood and stared at one another.

"She--she isn't down here," said Lucile at last. "Perhaps we had better go up and look among the boats."

Silently they walked back to where the hundred boats were looming in the dark, their masts like slender arms reaching for the moon. As they rounded a small schooner, they were startled by a footstep.

"Don't be afraid. It is only I," called a friendly voice. "Out for a stroll in the moonlight. Wonderful, isn't it?"

Marian recognized the young man of the schooner, Mark Pence. She had talked with him once before. He had helped her home with her two dozen cans of label-less fruits and vegetables. Having liked him then, she decided to trust him now, so in a few well-chosen words she confided their fears for their companion's safety.

"Shucks!" said the boy. "That'll be all right. She'll show up all right.

Probably went farther than she intended. But--sure, I'll take a turn with you through our little village of boats. Be glad to."

They wandered in and out among the various crafts. Scarcely a word was spoken until they came to the great black bulk of the scow inhabited by the Chinamen.

"I'll rout 'em out. Might know something," said Mark.

He knocked several times but received no response. He was about to enter when Lucile whispered:

"Wait a minute. Were--were you in the war?"

"A trifle. Not to amount to much."

"Know how to use a gas mask?"

"Well, rather. Six seconds is my record. Know that old joke about the 'quick and the dead,' don't you? I was quick."

Lucile smiled. She was holding out an oblong package fastened to a strap, also a small gla.s.s bottle.

"Take--take these," she whispered nervously. "You can't tell about those folks. Break the bottle if they go after you, then put on the mask. It's pretty powerful gas but does no permanent injury."

Mark smiled as he slipped the strap over his shoulder. "Nonsense, I guess," he murmured, "but might not be. Just like going over the top, you never can tell." He drew a small flashlight from his pocket, then pushed the door open.

He was gone for what to the girls seemed an exceedingly long time. When he returned he had little enough to tell.

"Not a soul in the place, far as I could see," he reported. "But, man, Oh, man! It's a queer old cellar. Smells like opium and chop-suey. And talk about narrow winding stairs! Why, I bet I went down--" He paused to stare at the scow. "Why that tub isn't more than ten feet high and I went down a good twenty feet. Rooms and rooms in it. Something queer about that."

The girls were too anxious for Florence's safety to give much attention to what he was saying.

"Well, we are greatly obliged to you," said Lucile, taking her bottle and gas mask. "I guess there's nothing to do but go back to the yacht and wait."

With a friendly good-night they turned and made their way back to the O Moo.

CHAPTER V A CATASTROPHE AVERTED

As Florence crouched in the dark corner of the deserted museum, many and wild were the thoughts that sped through her mind. Could she do it? If worse came to worst, could she strike the blow? She had the power; the muscles of her arm, thanks to her splendid training, were as firm as those of a man. Yes, she had the power, but could she do it? There could be no mincing matters. "Strike first and ask questions after," that must be her motto in such an extremity. There would be ample opportunity. A beast always hunts with nose close to the ground. The man would be a fair mark. The skate was as perfect a weapon as one might ask. Keen and powerful as a sword, it would do its work well. Yet, after all, did she have the nerve?

While this problem was revolving in her mind, the pit-pat of footsteps grew more and more distinct. Her heart pounded fearfully. "He's coming--coming--coming!" it seemed to be repeating over and over.

Then, suddenly, there flashed through her mind the consequences of the blow she must strike. The man must be given no chance to fight; one blow must render him unconscious. Whatever was done must be done well. But after that, what? She could not leave him alone in this great, deserted sh.e.l.l of a building. Neither could she await alone his return to consciousness. No, that would never do. She would be obliged to seek aid.

From whom? The police, to be sure. But then there would be a court scene and a story--just such a story as cub reporters dote on. She saw it all in print: "Three girls living in a boat. One pursued by villain. An Amazon, this modern girl, she brains him with her skate."

Yes, that would make a wonderful news story. And after that would come such publicity as would put an end to their happy times aboard the O Moo.

That would mean the end of their schooldays, just when they were becoming engrossed in their studies; when they had just begun to realize the vast treasures of knowledge which was locked up in books and the brains of wise men and which would be unlocked to them little by little, if only they were able to remain at the university.

The whole thing was unthinkable. She must escape. She must not strike the blow. There must be another way out. Yet she could think of none. Before her was an iron railing, but to go over this meant a drop of twenty feet.

Beyond her at the end of the balcony, towered a brick wall; at her back, an iron door. To her left there sounded ever more plainly the pit-pat of tiptoeing feet.

"I must! I must!" she determined, her teeth set hard. "There is no other way."

And yet, even as she expected to hear the shift of feet which told of a turn on the balcony, some ten feet from where she cowered, the pit-pat went steadily forward. She could not believe her ears. What had happened?

Then on the heels of this revelation, there followed another: The sound of the footsteps was growing fainter. Of a sudden the truth dawned upon her: The man was not on the balcony. He had not ascended the stairs. He was still on the floor below. Her sense of location had been distorted by the vast silence of the place. She was for the moment safe.

A wave of dizziness swept over her. She sank into a crumpled heap on the floor. Reviving, she was seized with an almost uncontrollable desire to laugh, but, clenching and unclenching her hands, she maintained an unbroken silence. At length, her nerves in hand once more, she settled down to watchful waiting. With eyes and ears alert, she caught every new move of the prowler.

As the sound of his footsteps died away in the distance, she settled herself to calmer thoughts. This place she was in was a vast cathedral of gloom. When the moon went under a cloud, blotting out the broad circle of light which fell from the vaulted dome, the darkness was so profound that she felt she must scream or flee.

Yet there was something magnetic about the place. She might have been held there even though she were not pursued. It was a place to dream of.