With the return of Franklin Blake to England, we can see that the investigation of the missing diamond takes on more urgency. Franklin has been the driving force of the investigation all along—first because he cared so much about Rachel and wanted to find her diamond and now because he equates the mystery of the diamond with the mystery of Rachel's cold treatment of him. Franklin is also the driving editorial force behind the assembled narratives of the diamond, and now we see why: Franklin is trying to clear his own name of suspicion in the theft of the diamond.

In an unusual plot twist, Wilkie Collins has the thief named just a little over halfway through the novel. Yet Franklin's guilt is still not apparent, for the mere fact that he does not remember committing the crime and believes himself innocent. We are never meant to distrust Franklin's assertion that he does not believe himself to have committed the crime, because we have been conditioned with reliable narrators. We may not have agreed with everything that Betteredge, Miss Clack, and Mr. Bruff asserted, but we never doubted the fact that they believed their assertions themselves and that they would not give false testimony. The possibility still remains here that Franklin has been framed, and Rosanna would stand as a likely agent of this framing. Franklin shows himself willing to believe this possibility, given Rosanna's background of dishonesty and thievery, but Betteredge stands up for Rosanna and urges Franklin not to dishonor her name now that she is dead.

This initial willingness on Franklin's part—to think ill of Rosanna—is in agreement with his character, which has been shown as questionable throughout the novel. Franklin's callousness toward Rosanna was evident in Betteredge's narrative and remains evident as he reads her letter. He is incapable, at first, of comprehending her love for him, and Betteredge has to warn him of his prejudice: "It's natural, sir, in you. And, God help us all! it's no less natural in her." Similarly, Franklin treats Lucy unthinkingly and rudely. The circumstances suggest that class privilege is at the root of Franklin's mistreatment of her. When Lucy says, "When you see a poor girl in service, do you feel no remorse?" Franklin answers, "Certainly not. Why should I?" These moments of ill judgment stand out because Franklin's narrative contains less character explanation than the other narratives. Betteredge, Miss Clack, and Mr. Bruff all included passages of explanation about themselves and all managed to reveal their personalities in their opinions and reporting of events. Franklin's narrative, however, contains little information about his background (beyond what we already knew) and reports events as a nearly third- person narrator—with little color or opinion.

The beginning of Franklin's narrative provides a return, in many ways, to the first section of the novel. The action moves back to Yorkshire, out of London, and old settings and characters reappear. The reintroduction of the Shivering Sands as a setting reminds us that Collins can rely heavily on place to set a mood when he wants. The Shivering Sands remain a site of duplicity. The Sands are both natural and unnatural, menacing to some and comforting to others (such as Rosanna), a place for hiding and a place of revelation. Franklin's perception of them under morning sunlight reflects this duplicity: "the bared wet surface of the quicksand itself, glittering with a golden brightness, hid the horror of its false brown face under a passing smile."