Francis Spufford’s novel "Cahokia Jazz" offers a distinctive blend of alternate history and detective noir, set in a reimagined post–World War I United States. The story centers around the independent state of Cahokia, located roughly where St. Louis exists today, where Native American communities have established an autonomous kingdom that blends traditional monarchy with Catholicism. This scenario diverges significantly from actual history, positing a world where smallpox did not decimate the indigenous population in the region, allowing a sovereign Native American state to flourish.

The novel follows Joe Barrow, a Native American murder detective in the Cahokia Police Department. He partners with Phineas Drummond, a white veteran and one of the first white individuals to treat Barrow without racial prejudice. Together, they investigate the murder of a white man whose death appears staged to mimic an ancient Aztec ritual, a discovery that threatens to ignite already tense racial conflicts within the city. Despite Cahokia’s independence, racial animosities persist, with the Native community and the Ku Klux Klan living side by side in the urban environment.

Spufford’s portrayal of the city of Cahokia is atmospheric and richly detailed, capturing the ambiance of early industrialization alongside the flow of the Mississippi River. As Barrow navigates the investigation, elements of jazz music and the tensions of identity and loyalty come to the fore. Barrow is also drawn into the political intrigues of Cahokia’s royal family when he receives a summons from "The Sun," the ruler, and becomes entangled with "The Moon," the Sun’s niece and a prominent society figure.

The narrative explores themes of race, identity, and belonging, as Barrow struggles with his own disconnection from native language and culture, having been raised outside Cahokia in a group home. His relationship with Drummond grows complex as questions arise about his partner’s motivations. Adding further depth, Barrow’s talent as a jazz pianist offers a contrasting avenue, representing both a personal refuge and potential path beyond the city’s fraught dynamics.

Spufford weaves a layered mystery that incorporates noir conventions, including a moody atmosphere, moral ambiguity, and social unrest, while building a world both familiar and strikingly altered. "Cahokia Jazz" complements Spufford’s earlier works, including the recently discussed novel "Nonesuch," which similarly combines alternate history with genre storytelling. Together, the books showcase Spufford’s inventive narrative voice and his interest in exploring history and identity through speculative frameworks.