The alternate history[1] novel tells the story of Cora, a slave in the Antebellum South during the 19th century, who makes a bid for freedom from her Georgia plantation by following the Underground Railroad, which the novel depicts as an actual rail transport system with safe houses and secret routes.

Cora is forced to kill a twelve-year-old boy to protect herself and Caesar, eliminating any possibility of merciful treatment should she be recaptured.

South Carolina is enacting a program where the government owns formerly enslaved people but employs them, provides medical treatment, and gives them communal housing.

North Carolina has recently decided to abolish slavery, using indentured servants instead, and violently executes any runaway slaves found in the state (as well as some freedmen).

While stopped in Tennessee, Ridgeway's traveling party is attacked by the free-born Royal and two escaped enslaved people, who release Cora.

Royal, an operator on the Railroad, begins a romantic relationship with Cora, although she remains hesitant because of a rape by other slaves in her childhood.

A small faction of freedmen, fearing that the presence of escaped slaves would ruin their peaceful lives, oppose the harboring of non-members of the community.

[5] Martin Ebel, who observed this parallel in a review for the Swiss Tages-Anzeiger, also observes that the "Freedom Trail", where the victims of North Carolinian lynchings hang from trees, has a historic predecessor in the crosses the Romans raised along the Appian Way to kill the enslaved people who had joined Spartacus' slave rebellion, written on by Arthur Koestler in his novel The Gladiators.

Ridgeway reminds Ebel of inspector Javert, the hero's merciless persecutor in Victor Hugo's Les misérables.

[19] The novel was voted the greatest of its decade in Paste and was third place (along with Jennifer Egan's A Visit from the Goon Squad) in a list by Literary Hub.

[21] While awarding the Pulitzer Prize, the committee recognized Whitehead's novel for a "smart melding of realism and allegory that combines the violence of slavery and the drama of escape in a myth that speaks to contemporary America".

[30] On August 5, 2020, a crater on Pluto's moon Charon was named Cora, after the character in the novel, by the International Astronomical Union's Working Group for Planetary System Nomenclature.

[31] It was announced in March 2017 that Amazon was making a limited drama series based on The Underground Railroad, written and directed by Barry Jenkins.