Underground begins with Cato finding the overseer, Bill, in his home badly injured from being stabbed in the neck after attacking Rosalee. Cato contemplates killing him until he hears Tom approaching and then yells for help. At The Big House, Ernestine searches for Rosalee, wondering if she had abandoned her morning chores. Tom summons her to Bill’s aide and there he reveals it was Rosalee who has injured him. They search the plantation for her, learning she and Noah have ran! Tom sets his slave drivers on their trail. Noah and Rosalee make their way to an outhouse. There she discards her dress while Noah finds a new dress hanging on a clothing line for her. He tells her the song of freedom, hoping she can make sense of it. Up North, Josey, a runaway slave holds John and Elizabeth hostage. He demands to know what has happened to his wife, Tippy. John insists he does not know who she is and that he has never owned slaves. Josey’s friend tries to reason him with him, feeling John and Elizabeth know nothing about slavery.
Ernestine goes to see Sam and demands to know what he knows about Noah. He inadvertently admits she was not suppose to run off him with him, and admonishes his mother for leaving him to work in The Big House years ago. She tells him now is now the time for their problems and that they must help Rosalee however they can. She demands he tell her everything. Josey makes Elizabeth serve them as if they were slaves and then demands they tell him what has happened to his wife. John continues to tell him he knows nothing and was just finishing law school years ago when Tippy was taken away from him. Josey punishes him for “lying” and tells him he will show what happens to slaves that lie to their masters. His friend leaves him, telling him he wants no part of what he is doing. Noah teaches Rosalee the song to freedom, so she can set out on her own. He tells her he is going back for the rest of The Macon 7. He recounts he first heard of free Blacks and that meeting Henry reminded him that he had to try and make it to freedom. Rosalee kisses him. The next morning, the slave catchers’ dogs pick up Noah and Rosalee’s scent. Noah tells her to run ahead of him as he deals with the dogs. She refuses, and pulls up a few plants from the ground and covers them with it just as the dogs make it to them. The flowers poison the dogs, preventing them from tracking them.