In 1970, a young Cincinnati Reds fan, struggling with his family's move from Ohio to northern Virginia, develops his first crush on a classmate amidst the once-every-17-year emergence of the Atlantic Brood X cicadas. His dream of becoming a Major League catcher is transformed into a career as a Navy officer, but the bond with his childhood friend remains strong, their lives forever intertwined by a pact to repatriate her missing brother from the Vietnam War.

Marked by star-crossed encounters aligned with the emergence cycles of the Brood X cicadas, their lives reconverge when he, a terminal rear admiral, and she, a rising foreign diplomat, embark on a mission to, once and for all, find out what happened to her brother, and bring him home.