What Jo Harding loves most about the summer is being able to retreat from annoying humans. Though her friends say she'd be happier with someone sleeping by her side, she insists that all she needs to be happy are her mules, her dog, and a trail into the backcountry. She has absolutely no time to teach the incompetent, if attractive, newcomer.

Daisy Lucero is an eager student from the start. Hired for work in the café, her real dream is to explore the High Sierra wilderness on horseback. While she would love to earn the respect of the handsome woman who inspired her adventure, she may have to settle for pestering her with songs and questions.

In the vast classroom of the California wilderness, each woman finds herself tested. Tests of perseverance for Daisy as she learns to ride, and tests of patience as Jo considers whether life is about more than riding alone.

It doesn't take either of them long, however, to realize that neither one of them needs a lesson in chemistry.