What is a summary for Chapter 10 in the book The Man Who Was Poe by Avi?I need a summary that explains the chapter.

Reunited with Dupin, Edmund tries to get the irrascible gentleman to tell him what he has discovered about Sis, but Dupin wants only to talk about Mrs. Whitman. Edmund relays a message to Dupin from Mrs. Whitman, instructing him to meet her at three-thirty in the cemetery behind the house, in private. Dupin offhandedly mentions that he has indeed found out something about Sis, but refuses to divulge any more information to Edmund, preferring to talk about Mrs. Whitman instead. In a desperate attempt to keep Dupin's attention, Edmund tells him that Mrs. Whitman was surprised that Dupin is in the area, and Edmund asks if he is here on business. Dupin confides in Edmund "a great truth." He says he is "a creator of the future." When Edmund asks what Sis's future will be, Dupin speaks cryptically and gloomily of death.

Dupin then asks Edmund to fetch some water to his room so that Dupin can ready himself to meet Mrs. Whitman. Edmund tells Dupin that in his absence, the room has been ransacked, his Aunty's trunk broken into, and a picture stolen. Back in the room, Dupin examines the trunk and notes that "the person who opened it had a key," and concludes that the one who murdered her is also the thief. Dupin then rudely dismisses Edmund and prepares to go to see Mrs. Whitman. As he leaves, Edmund blurts out the information that although it is true that his father was lost at sea, he has a stepfather as well. His stepfather had deceived his mother and stolen her money, and his mother had come to America to retrieve her money and divorce the evil man, whose name is Ratchett. Dupin is stunned, and tells Edmund that Ratchett is the man who fled so precipitously earlier that day when Edmund had gone to a clothing store to inquire about a coat. Dupin's demeanor becomes tormented, and he mutters that his and Edmund's lives are eerily similar except for "the death...of Sis." Edmund is overcome with despair, and as Dupin leaves the apartment, he instructs the overwrought boy to go to the docks and get information about a ship called The Lady Liberty; Dupin believes its watchman, Mr. Fortnoy, murdered Edmund's Aunty (Chapter 10).