Abilene is a twelve-year-old girl who has spent her life drifting from town to town with her father. Sent to stay in Manifest during the summer of 1936, she relies on her wits and a set of self-devised "universals" to make sense of her new environment. Resourceful and curious, she uncovers hidden letters and a mystery spanning decades, determined to understand her father's past connection to the town.

Gideon is Abilene's father, a wanderer who sends his daughter away to Manifest for the summer while he supposedly takes a railroad job in Iowa. Fiercely protective but haunted by a belief that he carries bad luck, he struggles with his past. His actions leave Abilene searching for answers about his history in the very town where he once lived.

Miss Sadie is a Hungarian immigrant and the town's resident diviner. Shunned by many in Manifest, she lives an isolated life until Abilene breaks one of her pots and begins working off the debt. Rather than telling the future, Miss Sadie shares vivid, sprawling stories about Manifest's past, guiding Abilene through the town's history.

Shady is the interim Baptist pastor of Manifest, an idiosyncratic man who lives in a building that serves as a church, a carpenter's shop, and a former speakeasy. He takes Abilene in for the summer at her father's request. Kind-hearted but carrying his own historical burdens, Shady operates as a quiet pillar of the community who harbors a deep loyalty to his friends.

Finn is a ruthless and manipulative conman whose criminal activities in Joplin cast a long, dark shadow over the 1917 timeline. He uses psychological manipulation and physical threats to control those around him, representing a severe danger that threatens to disrupt the peaceful refuge of Manifest.

Ned is a young man whose history in Manifest unfolds through a series of old letters and the stories told by Miss Sadie. Adopted by a local family, he eventually enlists in the military during World War I, leaving behind mementos and correspondence that become a central mystery for Abilene decades later.

Sister Redempta is a perceptive nun and the schoolteacher at Sacred Heart of the Holy Redeemer Elementary. She gives Abilene a summer storytelling assignment that inadvertently pushes the young girl to investigate the town. Compassionate and observant, she is known for assisting with difficult childbirths and quietly looking out for the marginalized members of Manifest.

Hattie Mae is the energetic reporter for the *Manifest Herald* and author of the "News Auxiliary" column. She is deeply invested in the town's history and happenings. She offers Abilene a chance to help organize her old articles, providing the young girl with a valuable window into Manifest's past.

Ruthanne is a local girl in Manifest who quickly befriends Abilene. Alongside Lettie, she serves as an eager companion in Abilene's summer investigations. Ruthanne is loyal, imaginative, and highly invested in tracking down the town's legendary spy, the Rattler.

Lettie is Abilene's other close friend in Manifest, characterized by her enthusiastic appetite and readiness for adventure. She joins Abilene and Ruthanne in their amateur sleuthing, bringing a sense of fun and childhood innocence to their search for the Rattler and their exploration of Manifest's mysteries.

Arthur Devlin is the ruthless owner of the Manifest coal mine during the 1917 and 1918 timeline. He exploits the immigrant workforce, demanding long hours and ignoring their welfare, all while holding a prominent position in the local Ku Klux Klan. His aggressive business tactics make him the primary adversary of the townspeople.

Lester Burton serves as Arthur Devlin's primary enforcer and right-hand man at the mine. He is a bully who takes pleasure in tormenting the immigrant workers and enforcing Devlin's harsh quotas. He actively attempts to thwart the townspeople's efforts to organize and purchase the valuable Widow Cane property.

Mrs. Larkin is an affluent and socially conscious woman in Manifest who cares deeply about lineage and propriety. She organizes the Victory Quilt project to support the war effort but reveals her prejudices by refusing to include a contribution from Miss Sadie, an act that reverberates through the town's history.

Pearl Ann is Mrs. Larkin's daughter, a popular girl in Manifest's past who holds a mutual affection for Ned Gillen. She struggles against her mother's strict views on lineage and social standing, showing more openness to the diverse community of Manifest than her parent does.

Sheriff Dean is the local law enforcement officer in Manifest during the 1918 timeline. He is a complex figure who enforces the law while simultaneously turning a blind eye to Shady's bootlegging operation in exchange for his own supply of illegal liquor.

Mr. Underhill is the local undertaker in Manifest. His secretive behavior in the cemetery makes him a prime suspect in the girls' investigation into the identity of the mysterious Rattler, leading them to closely monitor his movements around town.

Ivan DeVore is the telegraph operator and postman in Manifest. Because of his access to outside communications and the telegraph machine, Abilene briefly suspects him of being a spy. He helps Abilene send a crucial message at the end of the summer.

Velma (often referred to as Velma T.) is a local woman known for brewing a potent home elixir and vitamin revitalizer. Her concoction inadvertently becomes a crucial element in the town's desperate ploy against the mine owner during the 1918 influenza quarantine.

Hadley is a prominent, well-respected citizen in Manifest and Ned's adoptive father. He plays a leadership role in the town's resistance against the exploitative practices of the Devlin coal mine, helping to unite the disparate immigrant populations.

Charlotte is a wealthy student at Sacred Heart of the Holy Redeemer Elementary. Abilene quickly categorizes her under the "universal" of a snooty rich girl. She serves as an early social obstacle for Abilene as she tries to fit into the town's hierarchy.

Sheriff Nagelman is the law enforcement officer from Joplin, Missouri, and Sheriff Dean's brother-in-law. He is relentlessly pursuing the perpetrators of a murder, and his investigation eventually leads him to the borders of Manifest.