Underground begins with a meeting of the males slaves planning to run away. Moses reveals the lyrics to the songs imprinted on the cloth are code for directions to the North. They realize the River Jordan is code for the Ohio River. Noah tells them their plan is simple to to figure out a way off the plantation, around the other plantations, and up North. Sam begins to doubt his plans, due to their lack of detail and tells him he refuses to whipped for them not being prepared. Noah tells them all he needs them if they have a fighting chance and to decide then and there if they are going. They all agree to go with him, just as their clandestine meeting is interrupted by Cato. They fear he will betray them at first, but Noah assures him that he is on their side and going with them. Cato doubts his resolve, however, when he sees his motley crew. At The Big House, Rosalee is given the could shoulder by some of the other female house slaves who feel she is uppity because she does not come to the annual plantation dance.
The next day, Tom talks with the other plantation owners, revealing how he became an owner, despite his Northern upbringing. He hopes to sway their support for his bid to become one of Georgia’s next Senators. Elsewhere, August discovers his chickens have been killed by a wolf, and also finds his chicken coop has been raided of eggs when he notices a pair of footprints. He prepares to go after the wolf and the assailant, but his slave advises him against it and tells him he should spend more time with his son. August tells his son to get his rifle to go hunting with him. Back at the plantation, Noah tells Moses and his wife, Pearly Mae, they will need freedom papers to remain free in the North. She agrees, but tells him they will mean nothing without the master’s seal. Noah decides they need paper and ink first, and plan to get it from a traveling merchant. In Philadelphia, John and Elizabeth go to a brothel to meet with Mr. Still and enlist with The Underground effort. While waiting for him a man opens a crate to find a couple of slaves have mailed themselves to freedom, using Henry Brown’s idea. The woman does not survive.
As Tom and the plantation owners walk through his fields they marvel at how much cotton his slaves can pick and asks his overseer for the secret. Mr. Still arrives and tends to the surviving slave. He tells his story to him as Mr. Still resets his broken arm. Slave catchers invade the brothel, searching for the runaway. They manage to hide him below the floor boards. At the Big House, Ernestine looks on as Suzanna tells her son that James will be working in the field soon. Rosalee asks her has she ever dreamed of a better life, to which she explains she only tries to make her current one as good as it can be. Back in Macon, the merchant, Mr. Jack, makes his way to the plantation. He sells a few items to the overseer and a ribbon to one of the slaves. When he returns to the road Noah confronts him, demanding he give him some pen and paper. He warns him they would both be in trouble if he did that. Noah threatens to crack him in the head with the mallet he has with him. Cato manages to cover for him when the overseer questions him. He demands to know the full plan. Noah agrees to tell him at the plantation dance at The Shaw’s plantation that night. He tells him he will get what they need from her.
That night, Tom entertains the other plantation owners with cigars and brandy. When Rosalee comes in to serve them they try to flirt with her and one of them gropes her. Ernestine interrupts them and offers to get better wine for them, allowing her to escape. That night, she has has sex with Tom and tells him that James is never to work in the field. Tom agrees and they continue to have rough sex. Elsewhere, Moses tells Pearly Mae to prepare to write freedom papers for herself and their daughter, Boo, as well. She has reservations feeling they will slow them down. He tells her he will not leave without her and they will all enjoy freedom up North together. At the plantation dance, the slaves all enjoy themselves. Rosalee, too goes with them. There, Noah reveals that Ms. Shaw prefers the company of Black men and often picks him to be her “stallion” and have sex with her. Cato feels he is disgusting for having sex with her. Noah tells him the sex is just a distraction for him to grab her dead husband’s gun from his war chest. However, Noah tricks him and has the Shaw’s bodyguard tap Cato instead. He has sex with her, while Noah steals the gun. Elsewhere, August kills the wolf and has his son take it home to be cut up for meat. Later, his son tracks him down and finds him fighting with a runaway slave. He kills him in the ensuing conflict.
Elizabeth notices that the slave catchers are waiting outside to spot the runaway. John and Mr. Still act as decoys and have themselves beaten to get the slave catchers arrested for assault. The sheriff takes the catchers away. Cato returns and is furious with Noah for tricking him. Noah almost uses the gun on him, but Cato tells him he is not to be trusted and then tells him he is going with them still. Noah spots Rosalee sitting alone and then invites her to dance with him. She tells him she realizes what his tattoos are about, that they mean not letting White people define him. He asks her to run away with him.