Isa Benstein solved the problem in her own swift, characteristic fashion. She tore her dress from the shoulder so that the gauzy fabric hung over and hid the cruel red seam on her arm.

"Ask Lady Frobisher to come here," she said. "Then call my car and fetch my wraps. I quite see the necessity of making the thing look as natural as possible."

It was all done so smoothly and easily that no suspicion was aroused. Mrs. Benstein had simply had an accident with her dress, an accident that necessitated her immediate return home. She had had a charming evening, one that she was likely to remember for a long time. Her manner was easy and natural; she gave no impression of one who has escaped a nameless horror, perhaps a cruel death.

"I can slip away, thank you very much," she said. "Perhaps the gentleman who has been so kind will see me to my car. May I ask your arm?"

Harold bowed profoundly. It was just the opportunity he required. They threaded their way through the guests along the brilliantly-lighted corridor into the street where the car was waiting. Isa Benstein held out her hand in a warm and friendly grip.

"I am going to help you and Miss Lyne, if I can," she said. "Ask Miss Lyne to come and see me the first thing in the morning. After she has gone to bed to-night she will know and appreciate my request. Have you really solved the mystery of the two tragedies?"

"I am absolutely certain of it," Harold replied. "See, there is Sir Clement and that fellow—Hamid Khan, the man who was in the smoking-room, you know."

Mrs. Benstein looked eagerly out of the window. Her big eyes gleamed. "It is as I expected," she said. "I have made a discovery also, Mr. Denvers. If you will call on me after eleven to-morrow you will hear of something greatly to your advantage. Strange how fate seems to be playing into our hands to-night."

The car moved forward, the speaker was gone.

CHAPTER XXII.