partially enshrouded in darkness, it might betray her.

Dropping on hands and knees, she began to climb. A bit of glass cut her stocking. She did not notice that. A crumpled sheet of paper fluttered away; that was maddening. A broad patch of light from far above her head threw her out in bold relief for a second. For a second only. Then, leaping to her feet, she raced down the balcony and again entered the shadows.

Pressing a hand to her breast to still her heart’s wild beating, she listened intently.

Did she hear? Yes, there could be no mistake, there came a soft pit-pat, the footsteps of a person walking on tiptoes.

“Like one of those mounted tigers come to life,” she thought with a shudder.

Slowly she moved along the wall. If only she could reach a door! If she only could!

But that door was a distance of some fifty yards away. Could she make it?

Stealthily she moved forward. Stopping now and then to listen, she caught as before the stealthy pit-pat of footsteps. Once some object rattled on the floor and she heard a muffled exclamation. Then she caught a creaking sound—was he mounting the stair? Had the banister creaked?

Now she was twenty yards from the door, now ten, now five, and now—now she gripped its casing. Excitedly she swung around, only to find herself facing a rusted square of steel. The labyrinth of rooms was closed to her. She was trapped on a narrow balcony with no way to turn for escape.

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 glass 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.