With a bit of magical guidance from her small tourist town's Mrs. Claus, a bookstore owner named Sydney must make a decision about an unplanned pregnancy before Christmas. A mysterious gift from Mrs. Claus grants her insight in the form of vivid dreams about the most important women in her life, and she attempts to get insight and answers from the dreams as well as meaningful, long overdue conversations.

Holding Sydney back is her increasingly distant husband, who was never quite adjusted to his new life two years after an accident that took away his sight, and her 18-year-old shop assistant who is determined to save her from making the wrong decisions, even if it's against her will. The Cardinal Rule is a Christmas Carol-esque telling of a woman who must discover for herself what in her life is worth doing and risk losing the people closest to her in the process.