Winds of the World by Talbot Mundy

Men say Yasmini does not sleep. Of course, that is absurd. None the less, it is certain she must do much of her plotting in the daytime, for by night, until after midnight, she is always the Yasmini whom the Northern gentry know, at home to all comers in her wonderful apartment.

It is ever a mystery to them how she knows all that is going on in Delhi, and in India, and in the greater outer world, although they themselves bring her information that no government could ever suck out of the silent hills. They know where she keeps her cobras--where the strong-box is, in which her jewels lie crowded--who run her errands--and some of her past history, for not even a mongoose is more inquisitive than a man born in the hills, and Yasmini has many maids. But none--not even her favorite, most confidential maids--know what is in the little room that she reaches down a private flight of stairs that have a steel door at the top.