Though the novel features no literal spirits, it frequently references ghosts, establishing a motif that hints at the supernatural events that lurk around the narrative’s edges. The first such reference comes when Pendergast and Chambers pass by the “Ghost Swamp,” prompting a conversation about belief in the paranormal:

‘[Y]ou believe in the curse [of the swamp].’

‘I didn’t say that.’

‘No—you didn’t. So perhaps you’re more like Edith Wharton. […] She once said: I don’t believe in ghosts…but I’m afraid of them.’ (60-61).

Besides highlighting the two men’s characters—Chambers’s stubborn refusal to acknowledge the limits of rationality versus Pendergast’s greater acceptance—the exchange comes at a pivotal moment, when Pendergast and Chambers are en route to Mississippi to investigate the Diamondhead murder. The motif thus becomes intertwined with the novel’s central mystery, foreshadowing its quasi-supernatural underpinnings.

Other appearances of the motif likewise highlight the novel’s interest in the limits of conventional logic. The name of Dorion Magnus’s steamboat, the Fantôme, gestures to both his paranormal powers and to his “ghostly” nature; he is the most dangerous of the novel’s villains yet remains invisible for much of the narrative. That Pendergast has a “phantom” vehicle of his own—a Silver Wraith—highlights his comparable powers of intuition and evasion, further establishing the two men as counterparts.