High school junior Kendall Barrows is insanely together, smart, and laser-focused on attending NYU when she graduates. She's not one for spontaneous jaunts, and she hoards her savings for her future in New York. But when a DNA test reveals a genetic heritage her mother has kept from her, she feels a pull that's bigger than her goals, and quite possibly her budget.

Along with her best friend Mia and a "chaperone", Mia's college freshman brother—Kendall's nemesis—they're off on an unsanctioned road trip to meet Kendall's newly discovered half-brother. Kendall soon learns that sudden siblinghood is not as easy as she had imagined, but when a clue leads to another half-sibling on Instagram, the bend in the road on Route 66 leads them to Bend, Oregon. Here Kendall finds a sister with whom she shares a smile and a sense of wit. And from her, Kendall learns the identity of her father—but she must drive a thousand miles in two days to confront him or miss her chance completely.

Full of cinematic moments and unexpected detours, fights with her best friend and sparks with her best friend's brother, each stop brings new possibilities but also new pressures. And when Kendall unearths a family secret she never saw coming, she discovers that while map apps may work on terrain, they are far less reliable for the geography of the heart.