Three weeks

Paul Verdayne, wealthy English nobleman in his early twenties is caught embracing the parson's daughter. His parents decide to send him away to France and then Switzerland. In Switzerland, he sees a woman referred to only as "the Lady". The Lady is older, in her thirties. After several days of exchanging lustful glances, they actually meet. She invites him to her apartment where they share a sexual relationship for three weeks. Eventually, Paul learns that the Lady is actually the queen of a Russian dependency and that her husband, the king, is abusive towards her. She disappears after the titular three weeks and Paul is upset and returns to England. Paul later finds out that the Lady has given birth to their son. With his father's assistance, he finds out the Lady's identity; however, before they can meet again, she is murdered by her husband. Paul is upset and spends the next five years wandering around from country to country until he decides to make preparations to meet his son. (extract from Wikipedia).