Dowell begins Part II by describing the importance of August 4 in Florence's life. August 4 is the date of her birth, the beginning of her trip around the world, her first love affair, her marriage, her first encounter with the Ashburnhams, and her death. When discussing his wedding, Dowell flashes back to Florence's home in Stamford. Her aunts, the Misses Hurlbird, have warned Dowell not to marry their niece, but he disregards them as old and eccentric. Florence makes it clear that she would refuse to marry anybody who would not give her a home in Europe. But Dowell was pleased by this declaration; he knew his independent wealth would allow him to give her any lifestyle she chose, and that this would put him ahead of her other suitors. On August four, they eloped and the next day, boarded a ship to Europe.
Before they got on the ship, Florence warned Dowell that she had a heart condition like her Uncle John. She says that he must take care of her and pay very close attention to the bag in which she carried her heart medication. Dowell entrusted this bag to his black servant, Julius, who was so upset that his master was leaving him behind that he accidentally dropped the case. Dowell flew into an uncontrollable rage and beat Julius severely. He attributes Florence's later apprehension of him to the fact that she witnessed this scene.
Ten minutes after they boarded the ship, Florence's heart overtook her. They consulted the doctor immediately, and he told Dowell not to give any sexual affection to his wife. Remorseful, Dowell willingly complied. Florence tricks Dowell into believing she has a heart condition. Years later, when Leonora asks whether Florence ever regrets such deception, Florence excuses herself "on the score of an overmastering passion." Once they got to Paris, Florence resumed her affair with the ex-cabin boy, Jimmy. Together they thought of elaborate rules that Dowell must follow so as not to aggravate Florence's heart condition; the deception ran deep. But Jimmy got the best of Florence; he convinced Dowell that even crossing the English Channel would be too great a trip for Florence's weak heart. Florence was unable to fulfill her ultimate desire and return to Fordingbridge, the home of her ancestors.
Dowell reflects on Florence's two great affairs. He considers Jimmy low, fat, and unattractive, but he understands how Florence could have fallen in love with Edward. Dowell affirms that if he believed that Edward and his wife really passionately loved each other, he would not have done anything to separate them. Edward Ashburnham commits great, heroic deeds and everyone admires him. Dowell admits that Edward's greatest admirer is Nancy Rufford, the young girl the Ashburnhams took under their wing years ago.
In her affair with Edward, Florence was insanely jealous. If she even suspected that another woman was coming to visit Branshaw Manor, she would send a wire to England immediately and insist that Edward come to her in Paris. As time passed, Florence put more and more demands on Edward, making him kiss her at any moment of the day. She realizes that, even if she ends her marriage with Dowell, a divorced woman can never be lady of Branshaw Manor. Nevertheless, Florence tells Edward that she wants to divorce her husband and move with him to California. But Edward refuses; he knows that Leonora can and will make his life hellish if he allows Dowell to find out about the affair. Leonora is determined to protect Dowell from knowledge and pain.
After this explanation, Dowell returns in his story to the night of August four, 1913. That night Nancy and Edward went off to a concert at the Casino. Leonora asks Florence to run along with them and chaperone. Later, Leonora retires to bed and Dowell is sitting downstairs in the hotel with a man named Bagshawe. Suddenly Florence comes running through the door "with a face whiter than paper and her hand on the black stuff over her heart." When she sees that Dowell is talking to Bagshawe, she covers her face and runs to her room. But Bagshawe recognized her as Florence Hurlbird, who he had last seen coming out of Jimmy's room at five a.m. in the morning many years ago. Bagshawe shares this information with Dowell. Later, Dowell goes up to his wife's room to find her lying dead, an empty vial in her hand.