Shelley grinned. But there was no humour in his grin, merely an angry satisfaction that his tangled mind was involving others. Cunningham was surprised. Not for years had he known the chief to be so worried and upset. This case, he told himself, had “got Shelley’s goat,” and got it with a vengeance!

He listened. Shelley was speaking. “He must be here,” he said, with some satisfaction. “He has my orders not to go home until some information comes through—and if it had come through he would have brought it to me without delay.”

“Very good, sir,” said the constable, with the air of a sleepy butler, and retired.

Soon Sergeant Owens came in. He too was worried and upset. He realised that the disappearance of a noted Oxford don (and a don with a cousin in the Cabinet!) was something that simply cried out for investigation. And he was only too well aware that as yet his investigations had not brought in the results which those in authority would be certain, ere long, to demand.

“Now, Owens,” said Shelley briskly, “how is the search going?”

“Not too well, I’m afraid, sir,” answered Owens apologetically.

“Huh!” Shelley’s exclamation was a wordless grunt, but it was far more expressive of his annoyance and disgust than a long and sarcastic sentence would have been.

“We’ve traced the hotel where he usually stays in London, sir,” he said. “It’s the Prince’s, in Bayswater. He hasn’t been there for three months or more.”

“Go on.”

“He has various friends in London. Mr. Lucas, the scientist, who lives at Hampstead, is one. He’s not seen him, but he had a letter yesterday saying that Crocker would be in town within the next week or two, and would be calling. He said he’d drop him a line later, and let him know day and time and so on.”

“That’s a point that would be worth following up,” Shelley remarked. “Did he give any reason for this visit to London?”

“None. But then that’s nothing unusual, for Lucas was quite accustomed to receiving such letters from Crocker. He said that Crocker was often in town to do some work at the British Museum. He did a lot of reading and research there, and…”

Shelley interrupted him. “I’ve a ‘hunch,’ Owens,” he said. “Cunningham!”

“Yes, sir,” answered Cunningham, prompt as ever.

“Do you happen to know if there’s anyone on duty at the British Museum now?”

“Sure to be some caretakers or something, I should think,” said Cunningham.

“I didn’t ask what you think,” Shelley snapped. “I asked if you knew.”

“No, sir.”

“Well, ring up, and find out. If there’s a caretaker, get him to let us in, and tell him to get the keys of the Reading Room if he can. We shall be around there in a few minutes, and then we shall see what we shall see.”