In the small town of Fergus Falls, Minnesota—a place small enough where everyone knows each other's business—four unlikely girls become the best of friends. As freshmen in high school, Emily Larson, Grace O'Malley, Lindy Pulaski, and Rebecca DuPree form a talented singing quartet. They name their group SOLA—Sisterhood of Lake Alice—in recognition of the small lake that's just a few blocks from downtown.

Though coming from different walks of life, the girls are closer to each other than their real sisters; they share secrets they know will never be revealed to anyone else. But after high school graduation, the four go their separate ways, experiencing the good, the bad, and ugly in life—love affairs, babies born out of wedlock, illnesses, and family problems.

Each woman is at a turning point in their life when they return to Fergus Falls for their twentieth class reunion. They struggle with various problems—wearing the masks of success or learning to be honest—and together they rediscover the joy of friendships once more.