Barnaby, a maintenance worker at the City of Shells tourist attraction, is cleaning one of the enormous conch shells after hours while a storm builds in the distance. He hears screaming coming from inside Cornuta, one of the shells, and is frightened. He usually tries to leave promptly at seven because another worker, Raffy, told him that “this place turns into a motherfuckin’ ghost town after hours! The shells start singing” (157).

Cornuta is the smallest of the great conches, at 45 feet long, and is currently lying on her side for repairs. Barnaby goes to investigate and finds the screaming is real, because a young girl is stuck inside.

The girl is Lillith, usually called Big Red. She came to the City of Shells on a class trip. Her best friend, Laramie Uribe, who is two years older has also come. Her father owns the City of Shells, which is a collection of giant conch shells arranged to stand upright on the beach. Laramie, in seventh grade, tells Big Red, who is in fifth, stories of her sexual exploits—including the times she has had sex inside the great conches with Raffy.

The City of Shells turns out to be disappointing, and the beach, polluted.