Summering on Cape Cod in 1985, precocious young Lily befriends an enigmatic girl her age named Mesa. Through their shared time biking the quaint land and exploring the depths of their true selves, they unearth powerful feelings for each other.
Lily Peony is a precocious sixteen year old girl who spends her summers on Cape Cod with her grandmother Anna. Throughout the previous years vacationing, the Peony's grew close with the Valentine's, a Cape-native family consisting of single-mother Velma and her teenage son John.
During the summer of 1985, after being away from the peninsula for some time, Lily and John find themselves pursuing a mature and unexpected romance which has them both falling quickly for each other. Perhaps it's those new teen hormones or how puberty has become the two of them, an attraction is sparked almost instantly when the families share an outdoor dinner together in the Valentine's backyard on one of the Peony's first evenings back on Cape. Soon, John and Lily are spending a lot of time together and the chemistry, at times, seems a bit too heavy for Lily.
That year, she also happens to meet Mesa - a teenage girl who is fascinating to Lily for her undeniable confidence and indescribable beauty. Mesa takes a clear interest in befriending Lily, intrigued by her quiet and mature nature. Through their shared time together biking around the quaint land, swimming and listening to music, Lily realizes her feelings for Mesa are rather different from her feelings when she is with John. While there is certainly chemistry in both relationships, there is more of a fire between the girls, which Lily vaguely vocalizes to Anna at one point when seeking her advice: should she follow her heart or choose to stay in a more socially-accepted binary. This provokes Lily's internal struggle to identify herself and feelings for Mesa over her seemingly more traditional, yet less passionate, relationship with John during a summer she will never forget...the Summer of Mesa.
