And Siward went on: "I knew perfectly well what sort of women I was to meet at that fool supper Billy Fleetwood gave; and you must have, too, for the girl you took in was no stranger to you.

...

Her name is Lydia Vyse, I believe." The slightest possible glimmer in the elder man's eyes was all the answer he granted.
"What happened," said Siward calmly, "was this: She bet me she could so disguise herself that I could safely take her into any club in New York.
I bet her she couldn't.

I never dreamed of trying.

Besides, she was your--dinner partner," he added with a shrug.
His concentrated gaze seemed at length to pierce the expressionless surface of the other man, who moved slightly in his chair and moistened his thin lips under the glossy beard.
"Quarrier," said Siward earnestly, "What happened in the club lobby I don't exactly know, because I was not in a condition to know.