Once, however, he chanced to look up at her.  Something in her face must have impressed him.  Turning, he flung down the cards in disgust.  “That’s enough for to-night,” he exclaimed, rising and draining another glass on the tray.

“Luck will come your way soon again,” urged Bella.  “It all averages up in the end, you know.  It has to.”

“How did you enjoy the evening!” insinuated Bella.

“Very much,” replied Constance enthusiastically.  “It is so exciting, you know.”

“You must come again when more of my friends are here.”

“I should like to.  But to-night was very nice.”

Halsey looked at her contemplatively.  She had risen to go.  As she took a step or two toward the door, still facing them, she found Halsey at her side.

“Shall we go over to Jack’s for a bite to eat?” he whispered.

There was as much of appeal in his undertone as of invitation.

“Thank you.  I shall be glad to go,” Constance assented quickly.

There was something about Haddon Halsey that interested her.  Perhaps Bella and Watson exchanged a knowing glance as she crossed the hall for her wraps.  Whatever it was, Constance determined to see the thing through to a finish, confident that she was quite able to take care of herself.

Outside the raw night air smote dankly on their fevered faces.  As they walked along briskly, too glad to get into the open to summon a car, Constance happened to turn.  She had an uncomfortable feeling.  She could have sworn some one was following them.  She said nothing about a figure a few feet behind them.

The lively, all-night restaurant was thronged.  Halsey seemed to throw himself into the gayety with reckless abandon, ordering about twice as much as they could eat and drink.  But in spite of the fascination of the scene, Constance could not forget the dark figure skulking behind them in the shadow of the street.

Once she looked up.  At another table she could just catch a glimpse of Drummond, of the Burr Detective Agency, alone, oblivious.

Never did he look at them.  There was nothing to indicate that he was even interested.  But Constance knew that that was the method of his shadowing.  Never for a moment, she knew, did he permit himself to look into the eyes of his quarry, even for the most fleeting glance.

She knew, too, that there must be some psychological reason for his not looking at them, as he otherwise must have done, if only by chance.  It was the method followed by the expert modern trailer.  She knew that if one looks at a person intently while in a public place, for instance, it will not be long before the gaze will be returned.  Try as she would, she could not catch Drummond’s eye, however.

Halsey, now that the strain of the game was off, was rattling along about his losses in an undertone to her.

“But what of it?” he concluded.  “Any day luck may change.  As for myself, I go always on the assumption that I am the one exception—­ unlucky both at cards and love.  If the event proves I am right, I am not disappointed.  If I am wrong, then I am happy.”