In 2010, Lulu Miller was biking across the country, taking some time to clear her head for a new phase of life. And somewhere in Nevada, she ran into a guy named Jeff Viniard who was on a similar journey. They shared the road for two weeks, pedaling hundreds of miles together until Utah. Along the way, they got to be pretty close, and Jeff, a geologist by training, rekindled Lulu's long-lost love of rocks. But it turns out the ground beneath his own feet was shifting that summer... and he found himself desperately searching for some rock-solid evidence to help him figure out his future.