After the PTA of a conservative high school in Indiana bans same-sex couples from attending the annual prom, a gang of flamboyant Broadway stars try to boost their image by showing up to support two lesbian students.

An 18th birthday mushroom trip brings free-spirited Elliott face-to-face with her wisecracking 39-year-old self. But when Elliott’s "old ass" starts handing out warnings about what her younger self should and shouldn't do, Elliott realizes she has to rethink everything about family, love, and what's becoming a transformative summer.