Pat rushed to the door, out upon the porch, and down to the street. Dr. Horker followed her to the entrance and stood watching her as she darted toward the dejected figure beside the car.

"Nick!" she cried. "I'm here, Honey. You heard me, didn't you?"

She flung herself into his arms; he held her eagerly, pressing a hasty, tender kiss on her lips.

"You heard me!" she murmured.

"Yes." His voice was husky, strained. "What is it, Pat? Tell me quickly—God knows how much time we have!"

"It's Dr. Carl. He'll help us, Nick."

"Help us! No one can help us, dear. No one!"

"He'll try. It can't do any harm, Honey. Come in with me. Now!"

"It's useless, I tell you!"

"But come," she pleaded. "Come anyway!"

"Pat, I tell you this battle has to be fought out by me alone. I'm the only one who can do anything at all and," he lowered his voice, "Pat, I'm losing!"

"Nick!"

"That's why I came tonight. I was too cowardly to make our last meeting—Monday evening in the park—a definite farewell. I wanted to, but I weakened. So tonight, Pat, it's a final good-bye, and you thank Heaven for it!"

"Oh, Nick dear!"

"It was touch and go whether I came at all tonight. It was a struggle, Pat; he is as strong as I am now. Or stronger."

The girl gazed searchingly into his worn, weary face. He looked miserably ill, she thought; he seemed as exhausted as one who had been engaged in a physical battle.

"Nick," she said insistently, "I don't care what you say, you're coming in with me. Only for a little while."

She tugged at his hand, dragging him reluctantly after her. He followed her to the porch where the open door still framed the great figure of the Doctor.

"You know Dr. Carl," she said.

"Come inside," growled Horker. Pat noticed the gruffness of his voice, his lack of any cordiality, but she said nothing as she pulled her reluctant companion through the door and into the library.

The Doctor drew up another chair, and Pat, more accustomed to his devices, observed that he placed it in such position that the lamp cast a stream of radiance on Nick's face. She sank into her own chair and waited silently for developments.

"Well," said Horker, turning his shrewd old eyes on Nick's countenance, "let's get down to cases. Pat's told me what she knows; we can take that much for granted. Is there anything more you might want to tell?"

"No, sir," responded the youth wearily. "I've told Pat all I know."

"Humph! Maybe I can ask some leading questions, then. Will you answer them?"

"Of course, any that I can."

"All right. Now," the Doctor's voice took on a cool professional edge, "you've had these—uh—attacks as long as you can remember. Is that right?"

"Yes."

"But they've been more severe of late?"

"Much worse, sir!"

"Since when?"

"Since—about as long as I've known Pat. Four or five weeks."

"M—m," droned the Doctor. "You've no idea of the cause for this increase in the malignancy of the attacks?"

"No sir," said Nick, after a barely perceptible hesitation.

"You don't think the cause could be in any way connected with, let us say, the emotional disturbances attending your acquaintance with Pat here?"

"No, sir," said the youth flatly.

"All right," said Horker. "Let that angle go for the present. Are there any after effects from these spells?"

"Yes. There's always a splitting headache." He closed his eyes. "I have one of them now."

"Localized?"

"Sir?"

"Is the pain in any particular region? Forehead, temples, eyes, or so forth?"

"No. Just a nasty headache."

"But no other after-effects?"

"I can't think of any others. Except, perhaps, a feeling of exhaustion after I've gone through what I've just finished." He closed his eyes as if to shut out the recollection.

"Well," mused the Doctor, "we'll forget the physical symptoms. What happens to your individuality, your own consciousness, while you're suffering an attack?"

"Nothing happens to it," said Nick with a suppressed shudder. "I watch and hear, but what he does is beyond my control. It's terrifying—horrible!" he burst out suddenly.

"Doubtless," responded Horker smoothly. "What about the other? Does that one stand by while you're in the saddle?"

"I don't know," muttered Nick dully. "Of course he does!" he added abruptly. "I can feel his presence at all times—even now. He's always lurking, waiting to spring forth, as soon as I relax!"

"Humph!" ejaculated the Doctor. "How do you manage to sleep?"

"By waiting for exhaustion," said Nick wearily. "By waiting until I can stay awake no longer."

"And can you bring this other personality into dominance? Can you change controls, so to speak, at will?"

"Why—yes," the youth answered, hesitating as if puzzled. "Yes, I suppose I could."

"Let's see you, then."

"But—" Horror was in his voice.

"No, Dr. Carl!" Pat interjected in fright. "I won't let him!"

"I thought you declared yourself out of this," said Horker with a shrewd glance at the girl.

"Then I'm back in it! I won't let him do what you want—anyway, not that!"

"Pat," said the Doctor with an air of patience, "you want me to treat this affliction, don't you? Isn't that what both of you want?"

The girl murmured a scarcely audible assent.

"Very well, then," he proceeded. "Do you expect me to treat the thing blindly—in the dark? Do you think I can guess at the cause without observing the effect?"

"No," said Pat faintly.

"So! Now then," he turned to Nick, "Let's see this transformation."

"Must I?" asked the youth reluctantly.

"If you want my help."

"All right," he agreed with another tremor. He sat passively staring at the Doctor; a moment passed. Horker heard Pat's nervous breathing; other than that, the room was in silence. Nicholas Devine closed his eyes, brushed his hand across his forehead. A moment more and he opened them to gaze perplexedly at the Doctor.

"He won't!" he muttered in astonishment. "He won't do it!"

"Humph!" snapped Horker, ignoring Pat's murmur of relief. "Finicky devil, isn't he? Likes to pick company he can bully!"

"I don't understand it!" Nick's face was blank. "He's been tormenting me until just now!" He looked at the Doctor. "You don't think I'm lying about it, do you, Dr. Horker?"

"Not consciously," replied the other coolly. "If I thought you were responsible for a few of the indignities perpetrated on Pat here, I'd waste no time in questions, young man. I'd be relieving myself of certain violent impulses instead."

"I couldn't harm Pat!"

"You gave a passable imitation of it, then! However, that's beside the point; as I say, I don't hold you responsible for aberrations which I believe are beyond your control. The main thing is a diagnosis."

"Do you know what it is?" cut in Pat eagerly.

"Not yet—at least, not for certain. There's only one real method available; these questions will get us nowhere. We'll have to psychoanalyze you, young man."

"I don't care what you do, if you can offer any hope!" he declared vehemently. "Let's get it over!"

"Not as easy as all that!" rumbled Horker. "It takes time; and besides, it can't be successful with the subject in a hectic mood such as yours." He glanced at his watch. "Moreover, it's after midnight."

He turned to Nicholas Devine. "We'll make it Saturday evening," he said. "Meanwhile, young man, you're not to see Pat. Not at all—understand? You can see her here when you come."

"That's infinitely more than I'd planned for myself," said the youth in a low voice. "I'd abandoned the hope of seeing her."

He rose and moved toward the door, and the others followed. At the entrance he paused; he leaned down to plant a brief, tender kiss on the girl's lips, and moved wordlessly out of the door. Pat watched him enter his car, and followed the vehicle with her eyes until it disappeared. Then she turned to Horker.

"Do you really know anything about it?" she queried. "Have you any theory at all?"

"He's not lying," said the Doctor thoughtfully. "I watched him closely; he believes he's telling the truth."

"He is. I know what I saw!"

"He hasn't the signs of praecox or depressive," mused the Doctor. "It's puzzling; it's one of those functional aberrations, or a fixed delusion of some kind. We'll find out just what it is."

"It's the devil," declared Pat positively. "I don't care what sort of scientific tag you give it—that's what it is. You doctors can hide a lot of ignorance under a long name."

Horker paid no attention to her remarks. "We'll see what the psychoanalysis brings out," he said. "I shouldn't be surprised if the whole thing were the result of a defense mechanism erected by a timid child in an effort to evade responsibility. That's what it sounds like."

"It's a devil!" reiterated Pat.

"Well," said the Doctor, "if it is, it has one thing in common with every spook or devil I ever heard of."

"What's that?"

"It refuses to appear under any conditions where one has a chance to examine it. It's like one of these temperamental mediums trying to perform under a spot-light."