Fern is on the verge of turning fifteen, a significant milestone in her life as a young Baha'i. In Fern's Faith, the age of fifteen represents the age of spiritual maturity — a time when she will leave childhood behind and take responsibility for the progress of her own spiritual existence. As she ponders the significance of her upcoming birthday, she engages her friends and family members in a series of deep and meaningful conversations. Much of their time is spent reading and discussing passages from the Long Obligatory Prayer, one of three prayers that every Baha'i over the age of fifteen is required to choose from and recite daily. These discussions cause Fern to think deeply about the mysteries of existence as well as about her own life and future.