The novel centers around Don Tillman, a brilliant yet socially awkward genetics professor who has never been on a second date. Convinced he is simply not wired for romance, he embarks on the Wife Project - a scientific test to find the perfect partner. Enter Rosie Jarman, who is everything Don is not looking for: she's impulsive, fiery, and working as a barmaid while searching for her biological father. When Don agrees to help Rosie with her own project, his orderly, evidence-based approach to life is turned upside down. Through a series of unconventional encounters, the pair embarks on an endearing journey that challenges Don's perceptions of love, partnership, and what it means to be "normal."

In this engaging sequel, the protagonist, a brilliant but socially awkward geneticist, faces the challenges of impending fatherhood. After marrying Rosie, the couple relocates to New York City, where he struggles to adapt to his new life and the unexpected news that they're expecting a baby. Determined to be the perfect father, he approaches parenthood with the same meticulous research and planning that he applies to his scientific work, leading to a series of humorous and heartwarming misadventures. As he attempts to navigate the complexities of marriage and family life, he learns valuable lessons about love, friendship, and what it truly means to be a parent.