"Jacob Have I Loved" is a coming-of-age novel that follows the story of Louise, a twin sister overshadowed by her talented and beloved sibling, Caroline. Set in a small fishing village on the Chesapeake Bay during World War II, Louise struggles to find her own identity and pursue her dreams amidst the challenges of family dynamics, societal expectations, and the limitations of her environment. As she navigates the complexities of adolescence, Louise must confront jealousy, resentment, and the search for self-worth, ultimately discovering the strength to forge her own path and claim her independence.

The book follows four best friends—Lena, Tibby, Bridget, and Carmen—who discover a pair of jeans that miraculously fits each of them despite their different body types. Dubbed the Traveling Pants, the jeans become a symbol of their friendship and a way to stay connected as they spend their first summer apart. As the pants circulate among the girls, they experience a series of personal growth and life-changing experiences, from first loves to family conflicts. The story is a heartwarming exploration of the bonds of friendship, the pains of growing up, and the belief that a bit of magic can appear in the most unexpected places.

The novel follows the unique life of "A," a mysterious being who wakes up each day in a different body, living as that person for 24 hours. With no control over whose life they will inhabit next, "A" has learned to follow certain rules to avoid disrupting the lives of the individuals they temporarily become. However, everything changes when "A" falls in love with a girl named Rhiannon while occupying the body of her boyfriend. This newfound connection challenges "A" to seek a way to be with Rhiannon despite the ever-changing physical identity, leading to a poignant exploration of love, identity, and the human experience.