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.
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.