It's the summer of 1966. Family camping is the rage. Boomer kids are everywhere. Star Trek is brand-new. Smartphones and social media haven't even been dreamt of yet. So summer crushes happen the old-fashioned way: young face to young face.

While scoping out sites for stargazing at Castle Rock Lake, 12-year-old Eric meets a girl from the next campsite over. Charlene and Eric are both gifted, highly articulate students: Eric in math and science, Charlene in art and composition. He shows her the constellations in the ink-black Wisconsin night sky; she sketches him and writes him poems. An attraction neither has ever felt before soon blossoms between them. Eric's sensible parents caution him that 12 is too young to fall in love, while Charlene's parents barely speak to each other, let alone her. She aches for the love she sees in Eric's family, and takes strength from the attention and kindness that Eric offers her.

For Charlene has a secret, one that cuts to the heart of who and what she is. When the conflict in her family threatens to end the campout early, she must explain that secret to Eric, and begs him to accept the vision she has of her own future. Facing the possibility that they may never see each other again, Eric and Charlene struggle to put words to the feelings that have arisen between them. They discover the answer in the language they both speak, and had spoken together all along: Complete sentences.