Holly Kennedy’s 2025 novel, The Sideways Life of Denny Voss, is a literary coming-of-age story narrated by its neurodivergent protagonist. Thirty-year-old Denny Voss lives a quiet, sheltered life in rural Minnesota with his adoptive mother, Nana-Jo. After a series of well-intentioned but chaotic mishaps, he is arrested for the murder of a local businessman and mayoral candidate. To aid his defense, Denny must recount the events of the past year to his court-appointed therapist, uncovering painful family secrets and confronting a world that consistently misunderstands him. The novel was longlisted for the 2025 Giller Prize and was chosen as a Giller Book Club selection. Kennedy is also the author of The Tin Box, The Penny Tree, and The Silver Compass.

Kennedy, a Canadian author, was inspired by Mark Haddon’s novel The Curious Incident of the Dog in the Night-Time to write from the perspective of a character with a developmental disability, drawing on her own experiences with anxiety and ADHD to shape Denny’s voice. She deliberately set the novel in the United States to engage with the societal crisis of gun violence, and she incorporated real Minnesota harassment law to ground the narrative’s critique of how the legal system interacts with cognitive difference. Through Denny’s earnest and often humorous narration, the novel explores the themes of Mistreatment of People with Disabilities in the Criminal Justice System, The Trauma of Gun Violence, and The Power of Unconditional Love.

This guide refers to the 2025 Lake Union Publishing edition.

Content Warning: The source text and this guide contain depictions of graphic violence, physical abuse, emotional abuse, ableism, ageism, antigay bias, bullying, cursing, sexual content, substance use, addiction, child sexual abuse, rape, pregnancy termination, animal death, illness, mental illness, child death, death by suicide, and death.

Plot Summary

Denny Voss, a 30-year-old man from Woodmont, Minnesota, with a developmental disability, finds himself incarcerated in the Woodmont County Jail. He is charged with the murder of local businessman and mayoral candidate Henry Tesky. His court-appointed therapist, Dr. Harland, gives him a blue notebook and asks him to write down the events of the past year to help his lawyer, Bridget Klein, build a defense. Denny lives with his adoptive mother, Nana-Jo, and works for the Department of Transportation (DOT) with his cousin, Angus. His narrative begins with his arrest at the bottom of Penguin Hill, where he crashed his sled, which was loaded with eight rifles and four boxes of bullets that had belonged to his late adoptive father, Papa-Jo. The police found that one of the firearms, a Smith & Wesson .38 Special snub-nose handgun, was the weapon used to kill Mr. Tesky. 

As Denny recounts his story, he reveals a series of mishaps and misunderstandings that have frequently put him at odds with the law, starting with his first arrest for kidnapping a belligerent neighborhood goose named Tom Hanks. Believing the goose is angry because it is separated from its mate in Canada, Denny drugs it with Benadryl-laced oatmeal, transports it to the border on his bicycle, and is subsequently tased and arrested by Canadian Border Services Agents. The judge sentences him to 100 hours of community service, during which he meets a woman named Nori and her six-year-old son, Theo, who has Tourette’s syndrome. Denny befriends Theo and helps him gain confidence at his swim lessons by bringing along his blind and deaf Saint Bernard, George.

Denny’s second arrest occurs when he is an unwilling participant in a bank robbery. Coerced at knifepoint by the robber, Denny assists by taping the other customers’ hands. When he has an anxiety attack, he sings the theme song from Toy Story, “You’ve Got a Friend in Me.” This enrages the robber, who hits him. Denny vomits on the man just as police storm the building. Initially arrested while holding the stolen money, he is later cleared of all charges and lauded as a hero. 

The true turmoil in Denny’s life, however, stems from his discovery of a series of family secrets. After a leaky pipe floods their basement, Denny snoops through a trunk that belongs to Lydia, Nana-Jo’s estranged daughter. Inside the trunk, he finds his own birth certificate, which lists Lydia as his biological mother. He is furious at the lifelong deception from Lydia, Nana-Jo, and Angus, who all knew the secret. A few months later, on the night of January 2, he finds Lydia’s high school diary and learns that his biological father is Tesky, who was Lydia’s married31-year-old basketball coach when she became pregnant at 17. The diary reveals that Tesky tried to force Lydia into an abortion and later paid her to sign a nondisclosure agreement. Denny confronts a shocked Nana-Jo, who claims she never knew the father’s identity. He then confronts Angus, who also denies knowing. Angus, who is about to leave for a vacation, makes Denny promise not to do anything until he returns. Denny enters a fugue state that night and has a fragmented memory of the events. The next morning, Tesky is found dead from a gunshot wound. When Nana-Jo learns that Denny has been arrested, she has a stroke that leads her to be hospitalized and unable to speak.

At the trial, prosecutor Reginald Easterville builds his case against Denny. He establishes motive, citing that Tesky had fired Nana-Jo from her longtime housekeeping job, hit Denny with his Tesla, and filed a harassment restraining order against him after Denny confronted him in a pharmacy. He also reveals that Denny’s fingerprints and DNA are on the murder weapon, which he had in his possession when arrested. Key witnesses testify against him. His neighbor, Mrs. Trout, recounts seeing him with the sled full of guns moments before his arrest. Angus is forced to testify that Denny, despite not having a license, knows how to drive, giving him the opportunity to have driven to Tesky’s home on the night of the murder. The most dramatic testimony comes from Lydia, who, under oath, reveals that Tesky was Denny’s father and that she had recently blackmailed him into paying for Nana-Jo’s knee surgery, solidifying Denny’s motive in the eyes of the jury. However, a pharmacist named Brenna Talmage testifies that Denny remained calm when Tesky verbally abused him in the drugstore. 

The trial takes an unexpected turn when Bridget receives a CD from Nana-Jo, who is still recovering in the hospital. The CD contains security footage from a hidden camera in the chandelier of Tesky’s foyer on the night of the murder. Bridget and Dr. Harland show the video to Denny privately before presenting it in court. The footage reveals Nana-Jo confronting Tesky after learning that he is Denny’s father. When Nana-Jo threatens to expose him as a sexual predator, destroying his mayoral campaign, Tesky brutally attacks her with a golf club. Dazed and injured, Nana-Jo retrieves the Smith & Wesson handgun from a stowaway bench where Tesky’s first wife, Irene, had hidden it. As Tesky lunges at her with a knife, Nana-Jo shoots him in self-defense. After reviewing the exonerating evidence, Judge Milton Saginaw dismisses all charges against Denny with prejudice.

Denny is released from jail, but the joy of his freedom is short-lived. The morning after he returns home, his beloved dog, George, dies peacefully in his sleep. With Angus’s help, he buries George at their favorite spot by Turtle Creek. Soon after, Nana-Jo is released from the hospital. She is in a wheelchair and suffers from aphasia, but Denny lovingly steps into the role of her caregiver. With legal help from Bridget and Irene Tesky’s sister, Toni Hale, Denny’s paternity is officially established, and he inherits 18% of Tesky’s multimillion-dollar company. Lydia returns and gifts Denny a Newfoundland puppy named Wilson. Still grieving George, Denny initially rejects the puppy. However, after discovering photos Lydia has taken that capture his life with a quiet tenderness, including a moving image of him with George, he begins to see her differently. When Lydia leaves for a work assignment, she leaves Wilson behind, and Denny slowly bonds with the puppy. The novel concludes with the annual neighborhood party at the firepit. As they all watch a movie projected onto the shed, Denny reflects on his tumultuous year. He accepts the puppy, Wilson, into his heart and texts Lydia that he is keeping him.