Set in the summer of 1989 in suburban Maryland, "The Possibility of Fireflies" centers on Ellie Roma (King), a teen who dreams of becoming a writer and must deal with her self-destructive mother, Susanna (Love), and her volatile metal-head sister. When Ellie falls in love with her older neighbor, an aspiring singer, she finds herself caught in the alluring undertow of a reckless rock 'n' roll freedom.