“No, I don’t think we want you to stay in attendance any longer, Mr. Moss,” said Shelley. “You’ve been perfectly frank with us, as far as we know; and I see no reason why you should not go home to your bed. Only don’t leave London without letting us know.”

“Thank you, sir,” replied Moss with every indication of profound gratitude.

“That’s all right. Don’t thank me. Thank the lucky stars that made you keep that letter and its envelope. If it hadn’t been for that we might well have suspected you,” Shelley told him and then, holding out his hand in a friendly manner, wished him good night.

As soon as the young man was gone, however, his manner changed instantly. From the quiet, almost languid friend, Shelley became the detective on duty, alert, active, and without scruple when pursuing his quarry. He picked up a telephone from his desk, and spoke a few incisive words into its receiver.

“Jim?” he asked. “Good. A young man has just left my office—handsome young Jew—and I want him shadowed night and day. Two best men you have, put on his track. Don’t let him budge an inch without a shadow.”

A question came from the other end of the wire—a question Shelley had expected—and he answered. “Dangerous? No; I shouldn’t really think so; but you never know. And there’s just an outside chance that he may be a murderer. See? So put the best men you have on his trail; and tell them to report back immediately if he attempts to leave London; and to arrest him on suspicion if it looks like flight, and they haven’t time to get through to headquarters. Got that? Good.” And he slammed the receiver down, and wheeled round in his chair to face a thoughtful-looking Cunningham.

“Well, Cunningham? What do you think of our Mr. Moss?”

Cunningham shrugged his shoulders non-committally.

“Very difficult to say, sir,” he replied.

“I agree. That’s why I’m taking no chances. I don’t know the identity of the lunatic whom we’re shortly going to chase in the north of England,” added Shelley, “but, as there is at any rate a possibility that he’s an accomplice of Moses Moss, I’m taking no chances with that gentleman. I don’t want him—if he is in on this—to slip through our fingers while we’re chasing the other fellow. See?”

Cunningham saw.

“Now,” added Shelley briskly. “Sheffield. I fear that Mr. Moss has taken up rather more time than I intended. So we shall have to find other trains. What ones are there?”

Again Cunningham scanned the time-table. “There’s one at twelve-fifteen, sir,” he announced at length. “Reaches Sheffield at four-thirty a.m. How will that do?”