Set in the 19th century, follows the fortunes of the brilliant Alma Whittaker as she comes into her own within the world of plants and science. As Alma's careful studies of moss take her deeper into the mysteries of evolution, the man she loves draws her in the opposite direction, into the realm of the spiritual, the divine and the magical. Alma is a clear-minded scientist; Ambrose is a Utopian artist. But what unites this couple is a desperate need to understand the workings of this world, and the mechanism behind all life.