When Nolan Grey receives news that his father, a once-prominent biologist, has drowned off Leap’s Island, he calls on Elsa, his estranged, older half-sister, to help pick up the pieces. This, despite the fact that he and Elsa have been avoiding each other for a dozen years. The two travel to their father’s field station, a wild and isolated spot off the Gulf Coast. Here, their father’s fatalistic colleagues, the Reversalists, obsessively study the undowny bufflehead, a rare sea duck whose loss of waterproof feathers proves, they claim, that evolution is running in reverse and humanity’s best days are behind us.
On an island that is always looking backward, it’s impossible for the siblings to ignore their past. Stuck together in the close quarters of their island stilt-house, and provoked by the absurd antics of the remaining Reversalists, years of family secrecy and blame between Elsa and Nolan threaten to ruin them all over again. As the Greys urgently trek the island to find the so-called Paradise Duck, their father’s final obsession, they begin to fear that they were their father’s first evidence that the future held no hope.