The Bigtree alligator wrestling dynasty is in decline, and Swamplandia!, their island home and gator wrestling theme park, formerly no. 1 in the region, is swiftly being encroached upon by a fearsome and sophisticated competitor called the World of Darkness. Ava's mother, the park's indomitable headliner, has just died; her sister, Ossie, has fallen in love with a spooky character known as the Dredgeman, who may or may not be an actual ghost; and her brilliant big brother, Kiwi, who dreams of becoming a scholar, has just defected to the World of Darkness in a last ditch effort to keep their family business from going under. Ava's father, affectionately known as Chief Bigtree, is AWOL; and that leaves Ava, a resourceful but terrified thirteen, to manage ninety eight gators as well as her own grief.