A mysterious figure boards a Mississippi steamboat on April Fools' Day, initiating a series of encounters that challenge the integrity and trust of the passengers. The protagonist, if one can be identified, assumes multiple guises to test the gullibility and moral fiber of those aboard the Fidèle. These interactions serve as a vehicle for the author to examine the nature of human sincerity and the prevalence of deception in a rapidly expanding nation. The narrative unfolds through a series of episodic dialogues, eschewing a traditional linear plot in favor of a philosophical exploration of character and motive.

Readers and critics frequently describe this work as a challenging, experimental text that anticipates many techniques of modernism. Discussion often centers on the elusive nature of the title character and the difficulty of pinning down a singular moral message within the shifting narrative. Many observers highlight the book's biting satire of American optimism and the inherent instability of identity in a commercial society. While some find the lack of a traditional resolution frustrating, others appreciate the intellectual rigor and the dark humor embedded in the author's final completed novel.