The story follows the lives of two characters, John and Mary Standish, who meet and fall in love. The novel explores their individual backgrounds, experiences, and personal histories, as well as the impact of their "yesterdays" on their lives in the present. The narrative delves into themes of love, destiny, and how one's past can shape their future.Harold Bell Wright was a prolific author whose works often contained moral and spiritual themes. "Their Yesterdays" is one of his many novels that reflects his storytelling style, which was popular with readers of the time. The book combines romance with moral and philosophical reflections, making it a representative work of early 20th-century American literature.