The following version of this book was used to create the guide: Fisher, Tarryn. The Wrong Family. Graydon House, 2020.

In Tarryn Fisher's novel The Wrong Family, the third person narrator alternates between Winnie and Juno's perspectives. Though the novel shifts frequently between past and present, the following summary employs a largely linear structure.

After Winnie meets and falls in love with Nigel, she is convinced she is on her way to creating the perfect life. They find a beautiful old house near the park, and begin trying for a baby. Six miscarriages later, Winnie is distraught and hopeless. Her social work at Illuminations Mental Health does not thoroughly satisfy her longings. At times she fears if she only took the job to prove to Nigel that she is a good person. While at Illuminations, she meets Josalyn, an 18-year-old with a troubled past. What begins as well-intentioned protectiveness over Josalyn, soon turns to obsession. Winnie becomes even more involved with Josalyn's life when she discovers Josalyn is pregnant. Shortly after the baby is born, Winnie steals him from his mother. On her way home, she gets into an accident and the infant dies. At home, she begs Nigel to help her cover the crime. He buries the baby in the crawl space under their house.

Not long later, Winnie miraculously gets pregnant with Samuel. She channels all of her energy into being a wife and mother, desperate to disassociate from her dark past. When her unstable alcoholic brother, Dakota, comes to stay with her family, tensions between Dakota and Nigel threaten to undo the family.

Meanwhile, a homeless woman named Juno, squats inside the family's hall closet. After years on the street, Juno first encounters Winnie, Nigel, and Samuel in the park near their house. She starts following them on their walks, listening to their conversations. One day she sneaks into their house and hides in the closet. Though she had not planned to stay, she makes the closet, and the crawl space beneath, her new home. While concealed inside, she listens carefully to the family's movements and conversations. One night she overhears Winnie and Nigel discussing an infant Winnie stole years ago. Convinced they are talking about Samuel, Juno becomes determined to discover the truth and return Samuel to his real family.

Over the course of several weeks, Juno leaves clues of her investigation around the house. Winnie discovers them and worries someone knows her secret and will turn her in. Terrified her past has come back to destroy her, Winnie tries to reestablish control over her life by fixing her marriage. However, she soon discovers Nigel is seeing another woman. So distracted by this network of troubles, Winnie fails to see how sick her brother really is. She is shocked, therefore, when Dakota storms into her home, murders Nigel, and threatens her life. Overhearing the drama, and realizing her mistake, Juno decides to save Winnie from her violent brother. Winnie and Samuel make it free. Juno lures Dakota into the crawl space, where she shoots him, and eventually dies as well.

Grateful that her secret is still safe, and that she and her son are okay, Winnie decides not to confess her crime. She sells the house in an attempt to move out.

Only a month after the new owners move in, they smell a pungent odor. While seeking out the scent, the husband discovers the infant's skeleton, and Juno and Dakota's bodies in the crawl space.