A Prize for Princes — Rex Stout

Beautiful and deadly, Aline Solini is a study in pure evil. First encountered in a Balkan convent about to be sacked by marauding Turkish forces, she is rescued by Richard Stetton, a wealthy American who becomes totally captivated by her. His wealth aids her to escape from Vasili Petrovich, the husband she tried to poison, and enter the highest social circles to meet men of power, where she continues to ply her sensual talents in intrigue and murder.