Madeline was once a strikingly beautiful young woman. Tall, with blonde hair, blue eyes, a lovely face, and a gorgeous figure. However, due to a tragic bicycle accident not long after her marriage, her life took a drastic turn. She grew older physically but remained mentally and emotionally a seven-year-old.
The story is narrated by Timothy Maciver, the son of Aaron's second wife. Mac discovers numerous details about his father's first wife from his Aunt Figgy. Figgy shares with him much of what occurred before he was born and during the years when he was too young to remember. Mac commences his story shortly before receiving the notice that his cousin, Buddy's son, has been killed in Afghanistan. Memories flood back about his growing-up years and living with Madeline. Buddy, his cousin who is two years older and has more knowledge of life, provides Mac with insights into what he should know. Mac looks up to this cousin, as at their young age, two years makes a significant difference.
After Madeline's accident, she becomes a patient at the hospital where Mac's mother, Julia, works as a nurse. Julia had attended Madeline and Aaron's wedding and is somewhat of a friend to Figgy. Julia, a small and plain woman who has no interest in styles, makeup, shopping, or other girlie pleasures, is the complete opposite of the beautiful Madeline. Aaron Maciver can barely recall Julia as a wedding guest; she is not a memorable character. After Aaron and Julia get to know each other, they get married. Then, Mac is born, and two years later, sister Louise. Mac often ponders that if Madeline's accident had never happened, he would not exist. The family group, including aunts, uncles, cousins, and the dominant grandma, spends long summers at a large, estate-like residence at Moose Lake in northern Wisconsin. Madeline always accompanies the large family group. Aaron and Julia would never consider placing her in a home for disabled people, despite the advice of others. She becomes their child, throwing temper tantrums, pouting, and crying. Mac and Louise, when they were very young, are unsure of who Madeline is - possibly a tall child who lives with the family or perhaps an older sister. Madeline loves to play games with small children until they grow too old, and then she has to find another group of small kids to be friends with.
The family lives in Chicago in a neighborhood filled with large families, a busy and active place. Buddy is a strong man, a hero type, who defends those who are victimized. He breaks a kid's nose for making fun of Madeline and her boyfriend, Mikey O'Day. Yes, Madeline has a boyfriend, a singer who performs the popular music of the times. He is a retarded man who gives Madeline some sense of self-worth. Eventually, she gets small jobs that make her feel worthwhile. Buddy is the hero, and Mac's mother is proud of him, yet she doesn't like his military ways. Mac's mother is a pacifist, against war and violence.
Mac tells his story, going back to his childhood and beyond, sharing his experiences of growing up with Madeline, who grows old but not into adulthood. Mac is now a doctor in a small town in Wisconsin and has three daughters. Another character is Russia, a black home worker who works for the Macivers and several other neighborhood families. She is almost like family, dedicated to the Macivers.
Madeline remains the Maciver's baby long after Mac and Lu grow too old to be babied. She climbs into bed with the couple, sits on Julia's lap, and fusses about food. Aaron becomes angry with this overgrown baby, but Julia never does. This is an interesting story of midwestern people. It is different, yet perhaps not so much. Does anybody ever truly grow up?