It was the last night of Madame De Lisle's engagement. She would make her final appearance before the world in the beautiful tragedy of "King Lear." To-morrow she would retire to the conventional cloister forever.

The theater was so densely packed that there was scarcely standing-room on this her farewell night.

Lord Valentine and his wife and mother-in-law were in his box from which they had scarcely missed a night of the three weeks.

Besides Mrs. Lyle's passionate love of the drama there was a subtle fascination in Madame De Lisle's strange resemblance to her youngest daughter that impelled her thither every night to gaze upon her with eyes that never wearied in looking on her loveliness. She could not have told why it was, but she was vaguely conscious of a troubled tenderness about her heart whenever she looked at the fair young creature and heard the talk of her going into a convent.

"She makes me think of poor Queenie," she whispered to Georgina that night. "I cannot help feeling sorry for her, she is so like what she was."

"The resemblance is startling, indeed," Lady Valentine whispered back, "but don't let Sydney hear you, mamma. She does not like to hear about it."

Sydney made no sign, but she knew very well what they were talking of.

She came to the theater every night, though she hated to be there. Jealousy drove her to look on her rival's face every night that she might also watch her husband.

Poor Sydney! She sat there pale and haggard, and wretched in her white satin and diamonds, looking with jealous, suspicious eyes at the beautiful and gentle "Cordelia," hating her for the fairness that Lawrence Ernscliffe loved.

Queenie's sacrifice, made at so costly a price to herself, had utterly failed to purchase her sister's happiness.

Captain Ernscliffe had a seat in another part of the house where Sydney could watch his every movement. Her heart swelled with bitter pain and passionate anger as she looked at him. He did not even seem to know that she was there. His dark, melancholy eyes never once moved from the graceful form of the unhappy "Cordelia" as she acted her part on the stage. When the curtain fell he dropped his eyes and never looked up again until his beautiful idol reappeared.

La Reine Blanche had never acted better. She gave her whole attention to her part. She did not seem to see that one pair of eyes had watched her with such wild entreaty and passionate love in their beautiful depths.

There was one box at which she never looked but once, and it was when, in obedience to her husband's command, "Bid farewell to your sisters," she slowly repeated:

Everyone in the house saw her brilliant eyes fixed on Lord Valentine's box as she repeated those words, but perhaps no one but the actress herself saw that Sydney's eyes drooped in shame and confusion, while a scarlet blush stained her cheek.

Ah, she, and no other, comprehended the bitter meaning of Queenie's words as she fixed her blue eyes mournfully on the sister who had wronged her so deeply.

"This is her last night," Sydney murmured to herself, "but is it true that she will go into a convent? I must see her, I must know the truth for certain. I will go round to her dressing-room and ask her."

When the act was over she complained of sickness and asked Lord Valentine to take her down to the carriage.

Lord Valentine complied and left her sitting in the carriage, the coachman mounting to his box.

But in a moment, before the two prancing horses had started, Sydney slipped out of the carriage so noiselessly that the man drove on never dreaming but that she was shut up within.

Then she ran round breathlessly to the private entrance of the theater. She told the man who kept the door that she had an engagement with Madame De Lisle and desired him to show her to that lady's dressing-room.

Two minutes later she found herself alone in the small apartment where the actress changed her costumes for the different acts and scenes.

Queenie had not yet come in. The manager had detained her a few minutes and Sydney had time to draw breath and look about her while she waited for her sister.

There was not much to see. The room was dingy and sparely furnished, as the dressing-room of a theater is apt to be.

Costumes were laid over the backs of chairs, and the maid who should have been guarding them was "off duty," gossiping, no doubt, with some humble attache of the place. There was little to interest one, and Sydney grew impatient.

Suddenly she saw a letter lying carelessly on the toilet table. She took it up and looked at it.

It was addressed to Madame De Lisle, and had never been unsealed.

"It has been left here during the first act, and Queenie has never seen it," she said to herself. "It looks like my husband's writing. I will see what he has to say to her."

Recklessly, desperately, she tore it open, and drew out the sheet of note paper.

"My Darling," it said simply, "meet me at the western door after the first act is over. I must see you a moment."

No name was signed to the mysterious note, but Sydney felt sure that it was her husband's writing.

"Queenie has deceived me," she said to herself, angrily. "She is in collusion with Lawrence. I might have known she would play me false!"

She looked about her hurriedly. A long, black silk circular, lined with fur, hung over a chair. She put it on over her white dress, caught up a thick veil, winding it about her head and face, and hurried out to the retired western door.

Outside in the darkness stood a tall, muffled form.

"Queenie, is it you?" he said in unfamiliar tones.

In a moment she realized her mistake. It was not her husband, but in the hope of unearthing some fatal mystery, she said softly:

"Yes, it is Queenie."

These words sealed her doom. The man sprang forward and caught her by the arm.

Something bright and slender gleamed an instant in his upraised hand and then was sheathed in her heart.

As her terrible scream of agony divided the shuddering air, he turned and fled from the scene of his crime.

But poor Sydney, the victim of her own misguided passion lay there dying, with the deadly steel of the assassin sheathed in her jealous breast.