Jake is a 35-year-old divorced high school English teacher who feels largely disconnected from the modern world. When presented with the opportunity to travel through a portal to 1958, he adopts the identity of George Amberson to exist safely in the past. He is fundamentally kind and idealistic, though his assumptions about his ability to change history often lack foresight. He takes a job as a substitute teacher in Jodie, Texas, while actively plotting to stop the assassination of President Kennedy.

Sadie is the newly hired librarian at Jodie High School, arriving in town to start fresh after fleeing a deeply troubling marriage. She is tall, somewhat clumsy, and highly intelligent. She quickly develops a strong emotional and physical bond with Jake, though his secret mission and falsified background force a wedge of lies between them.

Al is the pragmatic, chain-smoking owner of Al's Diner who discovers a time portal located in his pantry. He originally uses the portal to buy cheap meat for his restaurant before meticulously researching how to change world history. Diagnosed with terminal lung cancer, he recruits his regular customer, Jake, to finish his ambitious mission to save President Kennedy.

A volatile, angry young man who recently returned to the United States from the Soviet Union. He frequently clashes with his family and local community, harboring intense political ideologies and an inflated sense of self-importance. Jake monitors him closely for years to determine if he truly acts alone in his historical crimes.

Harry is a gentle, quiet janitor at Lisbon Falls High School who walks with a severe limp. He survived a horrific Halloween massacre committed by his father in 1958, a trauma that severely impacted his ability to learn and function in society. His tragic personal history inspires Jake to test the time portal by attempting to prevent the attack.

The sitting US President in the early 1960s. His scheduled visit to Dallas in November 1963 serves as the focal point for Al's theory that saving his life will prevent decades of future national trauma, warfare, and racial tension.

A wealthy, charismatic Russian expatriate who befriends Lee Harvey Oswald upon his return to the United States. He shares strong political opinions with Lee Harvey and introduces the young man to influential social circles. His presence raises Jake's suspicions regarding intelligence connections and true motives.

Harry Dunning's father, who presents a charming, joke-telling exterior to his grocery store customers. Beneath this pleasant facade, he is a violent alcoholic with a history of severe domestic abuse. He serves as Jake's first major test in attempting to physically alter the timeline.

A local Derry resident who closely watches Frank Dunning. His sister was Frank's first wife, and he harbors deep convictions that Frank murdered her and her infant child. He actively seeks revenge and crosses paths with Jake during the Halloween stakeout.

A far-right US Army general living in Texas who holds virulent white supremacist views. He survives an assassination attempt in April 1963. Jake uses the event surrounding this general to verify whether Lee Harvey Oswald acts as a lone shooter with his rifle.

Mysterious vagrants who linger near the 1958 exit of the time portal. They wear hats featuring a colored card that changes shades over time. They cryptically warn Jake that he does not belong in the past and use an unsettling, nonsensical word to address him, hinting at a deeper understanding of time travel.

Sadie's former husband, whom she met while in college. He presents a highly respectable exterior to her parents but harbors severe psychological disturbances regarding intimacy. He grows increasingly possessive, violent, and dangerous as Sadie attempts to start a new independent life.

Frank Dunning's wife and Harry's mother. She is the primary victim of Frank's violent temper and the central target of the impending Halloween massacre that Jake travels back in time to prevent.

A friendly, practical teacher in Jodie, Texas. He marries Mimi Corcoran and becomes a trusted confidant for Jake, offering advice on local gossip and occasionally helping Jake handle sudden, violent crises.

Lee Harvey Oswald's young Soviet wife. She struggles to adapt to life in the United States while enduring her husband's frequent physical and emotional abuse. Over time, she slowly builds a separate social support network in Texas to survive his volatility.

Jake's ex-wife, who previously competed in ballroom dancing with him. She initiated their divorce, accusing Jake of being entirely incapable of showing significant emotion during crises.

The outgoing librarian who precedes Sadie at the high school. She convinces Jake to take a full-time teaching position before announcing her own terminal cancer diagnosis and marrying Deke Simmons.

The sharp, observant principal of the school where Jake teaches. She investigates Jake's background and quickly discovers his falsified employment references, forcing him to make hard choices about his cover identity.

A large, athletic high school football player in Jodie. Jake mentors him and encourages his natural acting talent, inadvertently setting off a chain of unintended consequences in the boy's life.

A Jodie high school student and Mike Coslaw's girlfriend. She suffers a severe facial injury in an accident, prompting Jake and the community to organize a fundraising event to pay for her reconstructive surgery.