Mr. Sampson Longvale was taking a gentle constitutional on the strip of path before his untidy house. He wore, as usual⁠—for he was a creature of habit⁠—a long, grey silk dressing-gown, fastened by a scarlet sash. On his head was his silk nightcap, and between his teeth a clay churchwarden pipe, which he puffed solemnly as he walked.

He had just bidden a courteous good night to the help who came in daily to tidy his living-rooms and prepare his simple meals, when he heard the sound of feet coming up the drive. He thought at first it was the woman returning (she had a habit of forgetting things); but when he turned, he saw the unprepossessing figure of a neighbour with whom he was acquainted in the sense that Sir Gregory Penne had twice been abominably rude to him.

The old man watched with immobile countenance the coming of his unwelcome visitor.

“ ’Evening!” growled Penne. “Can I speak to you privately?”

Mr. Longvale inclined his head courteously.

“Certainly, Sir Gregory. Will you come in?”

He ushered the owner of Griff Towers into the long sitting-room and lit the candles. Sir Gregory glanced round, his lips curled in disgust at the worn poverty of the apartment, and when the old man had pushed up a chair for him, it was some time before he accepted the offer.

“Now, sir,” said Mr. Longvale courteously, “to what circumstances do I owe the pleasure of this visit?”

“You had some actors staying here the other day?”

Mr. Longvale inclined his head.

“There was some fool talk about a monkey of mine trying to get into the house.”

“A monkey?” said Mr. Longvale in gentle surprise. “That is the first I have heard of monkeys.”

Which was true. The other looked at him suspiciously.

“Is that so?” he asked. “You’re not going to persuade me you didn’t hear?”

The old man stood up, a picture of dignity.

“Do you suggest that I am lying, sir?” he said. “Because, if you do, there is the door! And though it hurts me to be in the least degree discourteous to a guest of mine, I am afraid I have no other course than to ask you to leave my house.”

“All right, all right,” said Sir Gregory Penne impatiently. “Don’t lose your temper, my friend. I didn’t come to see you about that, anyway. You’re a doctor, aren’t you?”

Mr. Longvale was obviously startled.

“I practised medicine when I was younger,” he said.

“Poor, too?” Gregory looked round. “You haven’t a shilling in the world, I’ll bet!”

“There you are wrong,” said old Mr. Longvale quietly. “I am an extremely wealthy man, and the fact that I do not keep my house in repair is due to the curious penchant of mine for decaying things. That is an unhealthy, probably a morbid predilection of mine. How did you know I was a doctor?”

“I heard through one of my servants. You set the broken finger of a carter.”

“I haven’t practised for years,” said Mr. Longvale. “I almost wish I had,” he added wistfully. “It is a noble science⁠—”

“Anyway,” interrupted Penne, “even if you can’t be bought, you’re a secretive old devil, and that suits me. There’s a girl up at my house who is very ill. I don’t want any of these prying country doctors nosing around my private affairs. Would you come along and see her?”

The old man pursed his lips thoughtfully.

“I should be most happy,” he said, “but I am afraid my medical science is a little rusty. Is she a servant?”

“In a way,” said the other shortly. “When can you come?”

“I’ll come at once,” said Mr. Longvale gravely, and went out, to return in his greatcoat.

The baronet looked at the ancient garment with a smile of derision.

“Why the devil do you wear such old-fashioned clothes?” he asked.

“To me they are very new,” said the old man gently. “The garments of today are without romance, without the thrill which these bring to me.” He patted the overlapping cape and smiled. “An old man is entitled to his fancies: let me be humoured, Sir Gregory.”

At the moment Mr. Sampson Longvale was driving to Griff Towers, Mike Brixan, summoned by messenger, was facing Jack Knebworth in his office.

“I hope you didn’t mind my sending for you, though it was a fool thing to do,” said the director. “You remember that we shot some scenes at Griff Towers?”

Michael nodded.

“I want you to see one that we took, with the tower in the background, and tell me what you think of⁠—something.”

Wonderingly, Michael accompanied the director to the projection room.

“My laboratory manager pointed it out to me in the negative,” explained Jack as they seated themselves and the room went dark. “Of course, I should have seen it in the print.”

“What is it?” asked Michael curiously.

“That’s just what I don’t know,” said the other, scratching his head, “but you’ll see for yourself.”

There was a flicker and a furious clicking, and there appeared on the small screen which was used for projection purposes, a picture of two people. Adele was one and Reggie Connolly the other, and Michael gazed stolidly, though with rising annoyance, at a love scene which was being enacted between the two.

In the immediate background was the wall of the tower, and Michael saw for the first time that there was a little window which he did not remember having seen from the interior of the hall; it was particularly dark, and was lighted, even in daytime, by electric lamps.

“I never noticed that window before,” he said.

“It’s the window I want you to watch,” said Jack Knebworth, and, even as he spoke, there came stealthily into view a face.

At first it was indistinct and blurred, but later, it came into focus. It was the oval face of a girl, dark-eyed, her hair in disorder, a look of unspeakable terror on her face. She raised her hand as if to beckon somebody⁠—probably Jack himself, who was directing the picture. That, at least, was Jack’s view. They had hardly time to get accustomed to the presence of the mystery girl when she disappeared, with such rapidity as to suggest that she had been dragged violently back.

“What do you make of that?” asked Knebworth.

Michael bit his lip thoughtfully.

“Looks almost as though friend Penne had a prisoner in his dark tower. Of course, the woman whose scream I heard, and who he said was a servant! But the window puzzles me. There’s no sign of it inside. The stairway leads out of the hall, but in such a position that it is impossible that the girl could have been standing either on the stairs or the landing. Therefore, there must be a fifth wall inside, containing a separate staircase. Does this mean you will have to retake?”

Jack shook his head.

“No, we can back her out: she’s only on fifty feet of the film; but I thought you’d like to see it.”

The lights came on again, and they went back to the director’s office.

“I don’t like Penne, for more reasons than one,” said Jack Knebworth. “I like him less since I’ve found that he’s better friends with Mendoza than I thought he was.”

“Who is Mendoza⁠—the deposed star?”

The other nodded.

“Stella Mendoza⁠—not a bad girl and not a good girl,” he said. “I’ve been wondering why Penne always gave us permission to use his grounds for shooting, and now I know. I tell you that that house holds a few secrets!”

Michael smiled faintly.

“One, at least, of them will be revealed tonight,” he said. “I am going to explore Griff Towers, and I do not intend asking permission of Sir Gregory Penne. And if I can discover what I believe is there to be discovered, Gregory Penne will sleep under lock and key this night!”