Some twenty-eight years before a hundred thousand people in a single day had pa.s.sed in and out along the aisles of this vast structure. That had been in the days of its glory. All--the rich, the poor, the cultured, the illiterate, the laborer, the street gamin--had peered at the marvels displayed between its walls. And now--now two beings haunted its vast corridors, the one pursuing the other. How strange life was!

A whiff of wind sweeping over the main floor sent a whirl of waste paper flying in circles halfway to the ceiling. Two tiny red eyes peered at her at a safe distance--then another and another.

"Rats," she whispered. "Three of them."

The pit-pat of feet became distinct again. Putting out her hand to grip the skate, she discovered that her fingers were too stiff for service.

She had grown cold without sensing it. Rubbing her hands together, she warmed them. Her limbs too had grown stiff. Rising silently, she went through a series of exercises which sent the blood coursing through her veins.

"Must get out of here some way," she told herself, "but how?"

Then suddenly she thought of the girls. They would be anxious about her, might come out to seek her, only to fall into a trap.

A trap? She thought of Lucile, slim, nervous. Lucile hovering as she had in the corner of that old Mission on that other night; thought too of the things Lucile had seen there; admired the nerve she had displayed.

But what did it all mean? She could but feel that it all was connected in some way; the note of warning tacked to the schooner; Lucile's experience in the Mission and her present one, all fitted together in one.

What was it all about? Were they innocently checkmating, or appearing to checkmate, some men in their attempt to perform some unlawful deed? Were these persons moonshiners, gamblers, smugglers, or robbers living in the dry dock? If so, who were they?

Again the sound of footsteps grew indistinct in the distance.

"Ought to be getting out of here," she told herself. "Getting late--horribly late and--and cold. The girls will be searching for me.

There's an open window over there to my right. Terribly high up, but I might make the ground though."

She listened intently, but caught no sound. Then stealthily, step by step, she made her way toward the window.

Now she was fifty feet away from it, now thirty, now ten. And now--now she dropped silently to the floor and crept to the opening. There was no gla.s.s; she was glad of that. Flattening herself out, she peered over the sill to the void below.

"Terribly far down. Easily thirty feet!" she breathed. "Two gratings; rotten too, perhaps. Ground frozen too."

She reached far down and, gripping the top of the nearest window grating, threw all her strength into an effort to wrench it free.

"That one's strong enough," she concluded; "but how about the other?"

Again she lay quite still, listening. In the distance she fancied she caught the pit-pat again.

"Better try it while I've got a chance," she decided.

With the care and skill of a trained athlete she swung herself over the window sill, clung to the grating with her toes; dropped down; gripped the grating with her hands; slid her feet to the grating below; tested that as best she could; trusted her weight to it; swung low; touched the ground; then in her stocking-feet sped away toward the nearest street.

Arrived at a clump of bushes which skirted the street, she sat down and drew on her shoes. Then with a loud "Whew!" she crossed the street and made her way toward the O Moo over a roundabout but safe route, which led her by the doors of closed shops and beneath huge apartments where some of Chicago's thousands were sleeping.

Her mind, as she hurried on, was deep in the mystery and full of possible plans as to the uncertain future.

"I suppose," she mumbled once, "we should give up the O Moo. Most people would say it was a wild notion, this living on a ship, but what's one to do? No rooms you can pay for, and who would give up a university education without a fight? What have we done? What are these people bothering us for anyway? What right have they? Who are they anyway?"

This cast her into deeper reflections. The face she had seen was not that of Mark Pence. Whether it was one of the Orientals living on the scow, or one of the fishermen living in their fishing smack, she could not tell.

She had never seen the fishermen. Even Marian had seen but two of them.

"Might not be any of these," she concluded with a shrug. "Might have been some night prowler who will never come back."

The two girls in the cabin of the O Moo had waited an hour. Lucile had fallen half-asleep. Marian had lifted a trap door and had started the small gasoline-driven generator which furnished them light and heat. The engine was racing away with a faint pop-pop-pop, when Lucile sat up suddenly.

"Marian," she exclaimed, "what did that boy say about the scow those Chinese people live in?"

"Why," said Marian, wrinkling her brow, "he said something about going down twenty feet."

"That seems strange, doesn't it?" Lucile considered for a moment.

"Yes, but then it was a winding stairway. Probably he isn't used to that kind. Perhaps he just thought it was farther down than it really was.

I--"

"What was that?" exclaimed Lucile, starting up. There had come a m.u.f.fled sound from below, barely heard above the pop-pop of the engine.

In a second Marian had stopped the generator. Each girl strained her ears to listen. It came again, this time more distinct; tap-tap-tap, a pause, then a fourth tap.

"Florence!" exclaimed Lucile springing for the door.

Three taps, a halt, then a tap was the signal for lowering the rope-ladder.

A moment later Florence was being dragged into the cabin and ordered to give an account of herself.

"Sit down," she said. "It's rather a long story. When I'm through you'll very likely be for leaving the O Moo in the morning, and I'm not so sure but that is the right thing to do. The cruise of the O Moo," she laughed a bit uncertainly, "gives some indication of turning out to be an ill-fated voyage."

With Lucile and Marian listening intently Florence told her story.

"Florence," said Lucile, when she had finished, "do--do you suppose that has anything to do with the old Mission affair I told you about?"

"Or the warning tacked on our hull?" suggested Marian.

"I don't know," said Florence thoughtfully, "It might. The point really is, though, are we leaving in the morning?"

She was answered by an emphatic:

"No! No!"

"Do you know," said Lucile a few moments later as she sipped a cup of hot chocolate and nibbled at a wafer, "I peeped into that room in the old Mission yesterday. The shutter had been replaced but I could see through the cracks. There really wasn't anything on the table. The candles and crucifix were there, but nothing on the old table--not anything at all.

I--I must just have imagined that face."

"I'm not so sure," said Florence mysteriously.

"Oh!" exclaimed Lucile suddenly, "You were going to tell me the story that face reminded you of--the story told by an old seaman."

"I will," said Florence, "but not to-night. Just look," she sprang to her feet, "it's after three o'clock and to-day is already to-morrow."