Jamie is a boy from Harlow, Maine, who grows up to be a rhythm guitarist struggling with heroin addiction. His early encounter with the charismatic minister Charles Jacobs sets the course for a lifelong, complex relationship. Naturally curious and musically gifted, Jamie frequently finds himself drawn into Jacobs's orbit over the decades as he seeks work and personal healing.

Jacobs is a charismatic Methodist minister with a deep passion for electrical engineering, often using science experiments to teach his youth fellowship. Following a devastating family tragedy, his faith in organized religion shatters, leading him on a lifelong quest to explore what he calls "secret electricity." He reinvents himself multiple times, working as a portrait photographer and a revival healer to fund his private obsession.

Mother is a mysterious, otherworldly entity who holds dominion over a dimension beyond the living world. Glimpsed primarily through disturbing dreams, visions, and the chaotic aftereffects of Charles Jacobs's electrical treatments, she represents a terrifying unknown. Her true nature and intentions remain deliberately opaque, causing dread in those who sense her presence.

Astrid is Jamie Morton's high school girlfriend and first love. Their relationship blossoms alongside Jamie's early musical career and is cemented during a fateful trip to an electrical pole named Skytop. Though they part ways after high school, her impact on Jamie's life proves profound, especially when severe health issues bring her back into his orbit years later.

Conrad is Jamie's athletic older brother who suffers a tragic accident on a skiing trip that leaves him mute. He becomes the subject of one of Charles Jacobs's early electrical miracles when the minister restores his voice using a custom device. This event deeply impresses the Morton family and secures their loyalty to the minister.

Claire is Jamie's only sister, whom he cares for deeply. Her life and the eventual tragedy she endures profoundly affect Jamie, contributing to the emotional pain he later attempts to numb with drugs. She serves as a poignant reminder of the Morton family's early innocence.

Laura is the matriarch of the Morton family. She deeply cares for her children and is the one tasked with delivering devastating news to Reverend Jacobs after his family's accident. She later battles severe illness, an ordeal that tests the moral frameworks of her adult children.

Dick is the patriarch of the Morton family. He works hard to provide for his children, particularly when trying to afford medical care after Conrad's accident. He maintains a grounded, realistic perspective on life's tragedies, even acknowledging the harsh truths in Jacobs's controversial sermons.

Andy is one of Jamie's brothers who eventually adopts deeply religious views. His strict moral framework causes friction within the family during difficult decisions regarding their mother's declining health.

Terry is one of Jamie's brothers who remains close to his roots in Harlow. He stays in the family home and maintains a strong connection to his childhood, eventually fixing up classic cars in the barn and hosting family reunions.

Patsy is Charles Jacobs's beloved wife. She is a bright presence in the Harlow youth fellowship, where she charms the children by playing Beatles songs on the piano. Her sudden involvement in a fatal car crash catalyzes her husband's dramatic loss of faith.

Morrie, affectionately nicknamed "Tag-Along-Morrie," is the young son of Charles and Patsy Jacobs. He is well-liked by the town's children, including Claire Morton. His tragic accident fundamentally alters the trajectory of his father's life and scientific pursuits.

Hugh is Jamie Morton's boss and the owner of a Colorado recording studio. Having once suffered from Ménière's disease, Hugh was cured by Charles Jacobs's electrical treatments. He now experiences bizarre visual aftereffects he calls "prismatics," which fuel his suspicion and curiosity about the former minister's current activities.

Brianna is the daughter of Hugh Yates's bookkeeper. She forms a romantic connection with Jamie and assists him in his extensive research into Charles Jacobs's past patients, tracking down obituaries and medical records to uncover the truth behind the electrical cures.

Georgia is Hugh Yates's secretary and bookkeeper, and the mother of Brianna. She is protective of her daughter and becomes highly concerned when Brianna gets too deeply involved in Jamie's obsessive research into the revival pastor.

Jenny is Astrid Soderberg's devoted partner and nurse. Desperate to find a cure for Astrid's terminal lung cancer, Jenny brings her to Charles Jacobs in a last-ditch effort for a miracle, unwittingly involving them in his dark experiments.

Mary Fay is a single mother who contracted variant Creutzfeldt-Jakob disease from a blood transfusion. Because of her rare, fatal condition, Charles Jacobs selects her as a crucial subject for his most ambitious electrical experiment.

Al is a musician who overcame a severe drug addiction with the help of Charles Jacobs. He becomes a devoted follower, working security and managing correspondence at Jacobs's estate in upstate New York.

Cathy is a young woman who volunteers for Charles Jacobs's lightning photography show. The dazzling portrait she receives leaves a profound and troubling psychological impact on her, foreshadowing the hidden dangers of Jacobs's technology.

Robert is a young boy seemingly cured of muscular dystrophy by Charles Jacobs's holy rings. Jamie and Brianna track his case closely, discovering that his miraculous recovery comes with severe psychological aftereffects.

Norm is a high school senior who recognizes Jamie's musical talent and invites him to join his band, Chrome Roses. He helps launch Jamie's early foray into the music scene and remains a friend into adulthood.

Kenny is one of Jamie's early bandmates in Chrome Roses. He eventually leaves the music scene to pursue a career in insurance but remains fond of his teenage performing days, reuniting with Jamie later in life.