"Ach was!" replied the prisoner, turning a tearstained face towards him, "I haf seen nothing, except old Mac's back vich vos right in vront of me, it vos so dark!"

"But couldn't you see the other person at all, not even the outline" persisted the Chief.

The prisoner made a gesture of despair.

"It vos so dark, I say! Nothing haf I seen! I haf heard only his step!"

"What sort of step? Was it heavy or light or what? Did this person seem in a hurry?"

"A little light tread... so! won, two! won, two!, and qvick like 'e think 'e sneak opstairs vithout n.o.body seeing!"

"Did he make much noise"

"Ach was! hardly at all... the tread, 'e vos so light like a woman's..."

"Like a woman's, eh!", repeated the Chief, as if talking to himself, "Why do you think that?"

"Because for vy it vos so gentle! The' staircase, she haf not sqveak as she haf sqveak when I haf creep away!"

The Chief turned to the plain clothes man.

"You can take him away now, officer," he said.

Barney sprang up trembling.

"Not back to the cell," he cried imploringly, "I cannot be alone.

Oh, gentlemen, you vill speak for me! I haf not had trobble vith the police this long time! My vife's cousin, he is an elder of the Shool he vill tell you 'ow poor ve haf been..."

But the Chief crossed the room to the door and the detective hustled the prisoner away.

Then the official whom they had seen before came in.

"Glad I caught you," he said. "I thought you would care to see the post mortem report. The doctor has just handed it in."

The chief waved him off.

"I don't think there's any doubt about the cause of death," he replied, "we saw the body ourselves..."

"Quite so," replied the other, "but there is something interesting about this report all the same. They were able to extract the bullet!"

"Oh," said the Chief, "that ought to tell us something!"

"It does," answered the official. "We've submitted it to our small arms expert, and he p.r.o.nounces it to be a bullet fired by an automatic pistol of unusually large calibre."

The Chief looked at Desmond.

"You were right there," he said.

"And," the official went on, "our man says, further, that, as far as he knows, there is only one type of automatic pistol that fires a bullet as big as this one!"

"And that is?" asked the Chief.

"An improved pattern of the German Mauser pistol," was the other's startling reply.

The Chief tapped a cigarette meditatively on the back of his hand.

"Okewood," he said, "you are the very model of discretion. I have put your reticence to a pretty severe test this morning, and you have stood it very well. But I can see that you are bristling with questions like a porcupine with quills. Zero hour has arrived. You may fire away!"

They were sitting in the smoking-room of the United Service Club.

"The Senior," as men call it, is the very parliament of Britain's professional navy and army. Even in these days when war has flung wide the portals of the two services to all-comers, it retains a touch of rigidity. Famous generals and admirals look down from the lofty walls in silent testimony of wars that have been. Of the war that is, you will hear in every cl.u.s.ter of men round the little tables. Every day in the hour after luncheon battles are fought over again, personalities criticized, and decisions weighed with all the vigorous freedom of ward-room or the mess ante-room.

And so to-day, as he sat in his padded leather chair, surveying the Chief's quizzing face across the little table where their coffee was steaming, Desmond felt the oddness of the contrast between the direct, matter-of-fact personalities all around them, and the extraordinary web of intrigue which seemed to have spun itself round the little house at Seven Kings.

Before he answered the Chief's question, he studied him for a moment under cover of lighting a cigarette. How very little, to be sure, escaped that swift and silent mind! At luncheon the Chief had scrupulously avoided making, the slightest allusion to the thoughts with which Desmond's mind was seething. Instead he had told, with the gusto of the born raconteur, a string of extremely droll yarns about "double crosses," that is, obliging gentlemen who will spy for both sides simultaneously, he had come into contact with during his long and varied career. Desmond had played up to him and repressed the questions which kept rising to his lips. Hence the Chief's unexpected tribute to him in the smoking room.

"Well," said Desmond slowly, "there are one or two things I should like to know. What am I here for? Why did you have me followed last night? How did you know, before we ever went to Seven Kings, that Barney did not murder old Mackwayte? And lastly..."

He paused, fearing to be rash; then he risked it:

"And lastly, Nur-el-Din?"

The Chief leant back in his chair and laughed.

"I'm sure you feel much better now," he said. Then his face grew grave and he added:

"Your last question answers all the others!"

"Meaning Nur-el-Din?" asked Desmond.

The Chief nodded.

"Nur-el-Din," he repeated. "That's why you're here, that's why I had you followed last night, that's why I..." he hesitated for the word, "let's say, presumed (one knows for certain so little in our work) that our friend Barney had nothing to do with the violent death of poor old Mackwayte. Nur-el-Din in the center, the kernel, the hub of everything!"

The Chief leant across the table and Desmond pulled his chair closer.

"There's only one other man in the world can handle this job, except you," he began, "and that's your brother Francis. Do you know where he is, Okewood?"

"He wrote to me last from Athens," answered Desmond, "but that must be nearly two months ago."

The Chief laughed.

"His present address is not Athens," he said, "if you want to know, he's serving on a German Staff somewhere at the back of Jerusalem the Golden. Frankly, I know you don't care about our work, and I did my best to get your brother. He has had his instructions and as soon as he can get away he will. That was not soon enough for me. It had to be him or you. So I sent for you."

He stopped and cleared his throat. Desmond stared at him. He could hardly believe his eyes. This quiet, deliberate man was actually embarra.s.sed.

"Okewood," the Chief went on, "you know I like plain speaking, and therefore you won't make the mistake of thinking I'm trying to flatter you."

Desmond made a gesture.