Linckes’ depressed spirits suddenly soared high. A little colour stole up to the roots of his brown hair.

“You bet I’ll never rest till I’ve found the man who’s doing the dirty on us all!” he said impulsively. “Would you—er—would you be pleased if I discovered who it is, Miss Caryu?”

Tony had become suddenly interested in her shoe-buckles.

“I—I hope you’ll do the deed, certainly,” she answered.

Linckes took his courage in both hands. “I mean to. And—and if I do succeed I’m going to ask you a question, Tony.”

“Oh—oh, are you?” had said Tony in a small voice,

NOT many days after his conversation with Tony, Linckes presented himself at Winthrop’s house, with nothing at all to report. He found Sir Charles writing at his desk. He barely looked up at Linckes’ entry, and the detective knew that one of his black moods was upon him.

“Oh, hallo!” said Sir Charles. “Sit down! Any news?”

“Not much. The butler is now wiped off the list of possibles.”

“Well, I never thought he was a possible.” Winthrop pushed his chair back impetuously. “I’m dead sick of the whole business! The wretched culprit, whoever he is, is just one too many for us.”

“I’m dashed if he is!” Winthrop’s ill-humour seemed to react on Linckes. “Hang it all, he must give himself away some time!”

“Why? He hasn’t done it so far.”

“Pretty soon he’ll be trying to bring off another little coup,” said Linckes savagely, “and then I’ll get him!”

“Hope you will, that’s all I can say. Help yourself to a cigarette.”

Winthrop pushed the box across to Linckes, taking out a cigarette himself. He lit it, and began to smoke in silence. Linckes glanced at him idly, and suddenly a furrow appeared between his brows. It struck him that Winthrop was smoking in a curious way, rather as though he were puffing at a pipe. Usually he inhaled with almost every breath, sending the smoke out through his delicately chiselled nostrils.

“If I didn’t know you loathed pipes, I should say you were in the habit of smoking one,” remarked Linckes.

The dark eyes looked an inquiry. “You’re treating that unfortunate cigarette as though it were one,” Linckes explained.

Winthrop laughed, throwing the cigarette into the fire.

“Am I? Well, I’m worried. I suppose it’s a nervous trick. I feel inclined to do something desperate. If only there were a clue!”

Linckes sighed.

“It’s all so hazy,” he complained. “You can’t even know for certain that the plans of the submarines were sold. You can’t prove it.”

“Well, if the fact of Germany building submarines almost in accordance with those plans isn’t proof enough, I’d like to know what is!” Winthrop retorted irritably.

“Oh, I believe they were sold all right, but it can’t be proved. ’Twasn’t as though the plans were stolen. There wasn’t even a sign of anyone having tampered with the safe. The room—”

“For goodness’ sake don’t let’s go all over it again!” Winthrop begged. “We’ve torn it to bits. Oh, yes, I’m getting peevish, aren’t I?” He smiled reluctantly. “You’d be peevish in my place.”