“Four o’clock,” he muttered. “How strange!”

“May I come inside, sir? Horse’ll be all right if there don’t come a bobby prowling round. If he ain’t a fool he’ll be under someone’s doorway, for there ain’t likely to be no burgling a time like this.”

“Shut the door, and come in here,” said Chester, shortly; and he led the way into his consulting-room, turned up the gas, and from a closet took a decanter and glass, filled the latter for the cabman, who was making a pool on the thick carpet, and then poured himself out a few drops from a small-stoppered bottle, added some water from a table filter, and tossed off the mixture.

“Thank you, sir, and hope that there’ll do you as much good as this here’s done me a’ready. Didn’t know you was a doctor.”

“Here’s a crown for you,” said Chester, taking the money from a little drawer.

“Five bob! Oh, thank ye, sir,” said the man, with a grin. “Makes a fellow feel quite dry. Sorry for your carpet, sir. Good-mornin’. I don’t think I want another fare.”

As the door was closed after the man, the potent drops Chester had taken began to have some effect, and it seemed as if the dawn was coming through the black cloud which separated him mentally from what had taken place overnight.

“The man’s right,” he muttered. “I must sleep. Good heavens! What a state my brain is in!”

“Is that you, Fred?”

He started as if he had been stung, and the dawn brightened as he replied sharply—