He turned to the neurologist.

"What do you recommend, doctor?"

"There's only one thing to do, Professor Duchard. We must place the girl in a hospital, where she can be taken care of properly and kept under observation."

The aged scientist nodded. "Yes. I thought that would be your suggestion."

"If you'll excuse me," the doctor continued, "I shall use your telephone to make the necessary arrangements."

He left the room.

Beside the bed, Mark Carter still stared dumbly down at the girl he loved. The girl who tomorrow—no, today, for it was nearly morning now—was to have become his wife. He tried to speak, but his throat was too twisted and thick with pain for words to come. His broad shoulders were slumped. His brown eyes blurred with tears. A queer, strained sound of awful grief tore itself from somewhere deep within his chest, like the moan of an animal in torment.

A hand touched his shoulder.

"Come, Mark. We can do no more good here."

Mute, stumbling, broken, Mark allowed Professor Duchard to lead him from the room. Down the hall. Into the old man's study.

"Sit down, my boy, and pull yourself together."

Mark dropped into the cool, fragrant depths of a timeworn leather chair. The professor relaxed in another.

"I want you to tell me your story again," Elaine's father said. "Think back carefully. Give me every detail."

Slowly, spiritlessly, Mark forced himself to concentrate on the happenings of the evening. His voice a dull monotone, he again recounted his story.

"This woman," probed Professor Duchard, his bright blue eyes stabbing into the other's brown orbs. "Tell me about her. What did she look like?"

Mark shrugged.

"She was only a reflection in a mirror, professor. It was Elaine. Probably the lighting gave me the illusion of someone else."

"Cease thinking of her as a reflection!" the savant retorted, his voice suddenly sharp. "You are a newspaperman by trade. You have been trained to observe closely. I want you to use those powers now. Think of this woman as a person. Describe her to to me as if she were one—"

"She looked like Elaine," said Mark, racking his brain for details. "She looked just like her. Only different, the way two identical twins are different. You know what I mean, professor? The way a person's individual personality sticks out of him in spite of his appearance—"

"Yes. I quite understand."

"Well, that was the way it was with this woman. She was Elaine, but she wasn't. There was something about her that didn't belong to Elaine." His brows knitted. "It seemed as if I'd seen her before, somewhere. Just like I'd known her, but couldn't remember just when or where."

A pause.

"It was her clothing that made us notice her, though. She wore a red satin dress with more white ruffles than I ever saw before. She had a red hat, too, with a big plume. Her hair was done in a different style than I've ever seen. All fixed up. And she wore gloves that reached to above her elbow."

He searched his weary mind for more details. Gave it up in despair,

"I don't know, professor. I can't remember any more. She was just like a picture of one of the women attending a Louis XVI ball in France—"

A sudden light sprang into his brown eyes. He stopped short in mid-sentence.

"That's it!" he cried. "I've got it! I know where I saw her before!"

Professor Duchard leaned forward, blue eyes flashing.

"Where?" he demanded. "Hurry, man! Out with it!"

"You've got a picture of her!" Mark exclaimed excitedly. "Right here, in this study!" He half-rose from the leather chair. Peered into the corner behind him.

"It's gone!"

The professor's face was suddenly pale.

"That picture called 'Elaine Duchard's Escape'? The Jerbette? Is that the one you mean?"

"That's it. That's the one. Where is it?"

"It is gone," the savant answered grimly. "A genuine painting by Gustav Jerbette is worth a great deal of money. And I am not a wealthy man. When Adrian Vance offered to buy it—"

"Adrian Vance! That snake! He's the one who gave Elaine the mirror—"

The white-haired scientist was on his feet, his eyes suddenly very bright and cold. The veins stood out at his temples.

"I want to see that mirror!" he rapped. "This is the first time you have mentioned that it was he who sent it. Come on!"

Together they hurried down the stairs to the little room where the wedding gifts were on display. Mark started across toward the mirror. The professor's hand shot out. Caught the younger man's arm.

"Stand back!" he cried in a terrible voice. "Do not go near that mirror. Above all, do not pass in front of it!"

Mark stared at the savant open-mouthed. His earlier black despair was gone, now, replaced by sudden, inexplicable hope.

"Why not? What's wrong?"

The other licked dry lips.

"Nothing, I hope. The chances are a thousand to one that I am wrong. Yet an idea came to me, my boy. An incredible idea, and a horrible one. And if it is right"—he shook his head slowly—"may God have mercy on Elaine!"

Carefully, then, they approached the mirror. The professor studied it through narrowed eyes from a vantage-point far to one side. At last he turned to Mark.

"Do you notice any defects or flaws in the surface of that glass?" he demanded.

His daughter's fiance nodded.

"The whole thing's out of kilter, professor."

"How would you describe it? What do you mean by 'out of kilter'?"

Mark considered for a moment. Then:

"The impression I get is that this mirror was poured into a circular form, instead of being cut to shape. And that while it was still molten, something struck it in the center, so that little ripples formed in the glass, all the way from the center to the outer edge."

It was the scientist's turn to nod.

"Precisely my own view."

Moving away, he selected a candlestick and candle from among the gifts on display. He handed it to Mark.

"I want you to move this stick in front of that glass," he instructed. "However, you must be careful to stand well to one side, so that you, yourself, will not be reflected."

"What's the angle, professor? What do you expect to find? What's wrong with this mirror?"

The elder man shook his head, moved to a point where he could watch the surface of the glass.

"I do not know what to expect," he said. "I may be completely on the wrong track."

But his flashing eyes denied the words.

Seething with curiosity and excitement though he was, Mark carefully carried out his instructions. He moved the candlestick back and forth and up and down until it had been reflected from every inch of the mirror. And the farther he progressed, the more excited Elaine's father became.

"The reflection is perfect!" the old man cried. "It is true! Nowhere is there a single sign of distortion!"

"Yes. Of course it's true." Mark was a little bewildered. "Why shouldn't it be? Isn't every looking-glass supposed to throw back a reasonably exact image?"

"Of course, of course!" The scientist was impatient. "But can you not see the difference?"

"The difference? What difference?"

"Mark: this is not an ordinary mirror. That is what I mean! It denies every law of optics! Glass as full of waves and ripples as this apparently is should return hideously distorted reflections. Yet it does not do so!"

"But what—"

"We shall see. Come on! Bring the mirror to my laboratory."

Hesitating only long enough to throw a tablecloth across the face of the glass, the old man hurried out. Mark strode along in his wake, the heavy mirror in his arms. Together, they left the house and followed the bricked path to the little laboratory structure located at the far end of the lot.

"Set it down here, in this rack," the professor instructed, indicating an easel-like arrangement in one corner. He