Madeleine Lee, the daughter of an eminent clergyman, is a 30-year-old widow of independent means living in New York City. Five years ago she lost, in quick succession, her husband and her baby. She used to be "a rather fast New York girl" before her marriage but now is virtually unable to get over the great loss she has suffered.
Bored stiff by New York society, Madeleine Lee decides to go to Washington to be close to the hub of politics. Together with her sister Sybil Ross, she arrives in the capital, and in no time her salon becomes the meeting place of important people in the city. Although she has no intention whatsoever of becoming romantically involved, two men eventually emerge from the group gathering around her both of whom would very much like to marry her: John Carrington, who is truly and deeply in love with her; and Silas P. Ratcliffe, whose marriage to Madeleine Lee would help him advance his political career.
Over the months, Madeleine Lee gets more and more insight into the machinations at the center of political life. Seeing his chances fade, Ratcliffe devises a sophisticated scheme to get rid of John Carrington: he secures a post abroad for his rival, whoâas the job is rather well-paid and his family has little moneyâcannot but accept the offer. Step by step, Ratcliffe manoeuvres Madeleine Lee into a difficult position in which he thinks the only choice left to her will be to marry him. Carrington, however, has left behind a sealed letter in which he accuses Ratcliffe of being corrupt. In particular, he accuses him of having taken graft during the election campaign eight years ago. All evidence, Carrington adds, has been destroyed, so it is his word against Ratcliffe's. The latter of course denies all allegations, but Madeleine Lee is so shocked at the revelation that she turns down Ratcliffe's proposal of marriage. Furious, Ratcliffe leaves Madeleine's house, only to be accosted and ridiculed by his arch-enemy Baron Jacobi, the Bulgarian minister. There even ensues a brief scene of physical violence between the two, but at the very last moment Ratcliffe, whose career would be ruined otherwise, is able to keep his wrath in check.
Disillusioned by politics, Madeleine Lee now wants to go abroad, preferably to Egypt. Sybil, who has become Carrington's confidante, writes him a letter in which she tells him he should try again to win her sister's heart once they have returned from their tour.

Question: Who is Sybil Lee to Madeleine Carrington?
Answer: Her sister.
Alternative answer: her sister