Sir Brian surveyed him with mild surprise.

“Yes,” he replied; “I was for some time at the Embassy in Pekin.”

His guest nodded, blowing a ring of smoke from his lips and tracing its hazy outline with the lighted end of his cigar.

“I, too, have been in China,” he said slowly.

“What, really!  I had no idea.”

“Yes—­I have been in China...  I"...

M. Gaston grew suddenly deathly pale and his fingers began to twitch alarmingly.  He stared before him with wide-opened eyes and began to cough and to choke as if suffocating—­dying.

Sir Brian Malpas leapt to his feet with an exclamation of concern.  His visitor weakly waved him away, gasping:  “It is nothing... it will... pass off.  Oh! mon dieu!"...

Sir Brian ran and opened one of the windows to admit more air to the apartment.  He turned and looked back anxiously at the man in the armchair.

M. Gaston, twitching in a pitiful manner and still frightfully pale, was clutching the chair-arms and glaring straight in front of him.  Sir Brian started slightly and advanced again to his visitor’s side.

The burning cigar lay upon the carpet beside the chair, and Sir Brian took it up and tossed it into the grate.  As he did so he looked searchingly into the eyes of M. Gaston.  The pupils were extraordinary dilated....

“Do you feel better?” asked Sir Brian.

“Much better,” muttered M. Gaston, his face twitching nervously—­“much better.”

“Are you subject to these attacks?”

“Since—­I was in China—­yes, unfortunately.”

Sir Brian tugged at his fair mustache and seemed about to speak, then turned aside, and, walking to the table, poured out a peg of brandy and offered it to his guest.

“Thanks,” said M. Gaston; “many thanks indeed, but already I recover.  There is only one thing that would hasten my recovery, and that, I fear, is not available.”

“What is that?”

He looked again at M. Gaston’s eyes with their very dilated pupils.

“Opium!” whispered M. Gaston.

“What! you... you"...

“I acquired the custom in China,” replied the Frenchman, his voice gradually growing stronger; “and for many years, now, I have regarded opium, as essential to my well-being.  Unfortunately business has detained me in London, and I have been forced to fast for an unusually long time.  My outraged constitution is protesting—­that is all.”

He shrugged his shoulders and glanced up at his host with an odd smile.

“You have my sympathy,” said Sir Brian....

“In Paris,” continued the visitor, “I am a member of a select and cozy little club; near the Boulevard Beaumarchais....”

“I have heard of it,” interjected Malpas—­“on the Rue St. Claude?”

“That indeed is its situation,” replied the other with surprise.  “You know someone who is a member?”