The sound grew clearer and more unmistakably like a cab rattling quickly up the drive.

“It is a cab,” said Sherlaw.

They heard it draw up before the front door, and then there came a pause.

“Who the deuce can it be?” muttered Escott.

In a few minutes there came a knock at the door, and a servant entered.

“A new case, sir. Want’s to see Dr Congleton particular.”

“A man or a woman?”

“Man, sir.”

“All right,” growled Sherlaw. “I’ll come, confound him.”

“Bad luck, old man,” laughed Escott. “I’ll wait here in case by any chance you want me.”