Campbell builds an essay around one odd episode — crabs swarming ashore — in Leonora Sansay's Secret History; or, The Horrors of St. Domingo of 1808. The reading follows the crustacean backward into eighteenth-century natural history, where writers on the natural world had already loaded the animal with meaning about slavery, and specifically about the threat that enslaved people were thought to pose to European colonization.

Taken as an emblem rather than a stray detail, the swarm lets Sansay do two things at once: register American alarm at the Haitian Revolution and take the edge off that alarm by rendering it in the cool, classifying idiom of science.

Campbell treats the episode as evidence for a wider claim about the period's fiction — that political commentary often sits inside borrowed scientific description, and that early American literary study has something to gain from reading natural history alongside the novels.