Sarny is born in the slaves' cabin. Their master, Clel Waller, walks in and becomes angry when he realizes that it is a girl, instead of a boy. He states that a boy is worth a thousand dollars while a girl is worth nothing. But a promise has been made, so the baby girl is not sold. Instead, later when Sarny is older, her mother is sold so that Mr. Waller can recover his money. Sarny is then taken care of by another slave, Delie.
Sarny grows up and starts working on the plantation. Back at the house, Outlaw tries to get Delie to convince Mr. Waller to give him a pass so he can marry a girl named Egypt from another plantation. Delie is preparing a dress for Sarny so she can go to work at the master's house. Sarny is in charge of taking care of Wallers' young son, Homer, who is just a toddler and not 'housebroken' or potty trained.
The family and slaves then go to church, with Sarny standing in front with Homer. After the service, the Wallers have guests over for lunch, among them a doctor who later has a romance with Callie, Clel’s wife. Clel discusses the fact that his cotton is worth a lot of money. During the luncheon, Callie brings up that one of the slave boys wants to court a girl from another plantation, owned by Clel's brother. Clel immediately refuses stating that if they were to have a baby, it would give money to the wife’s plantation instead of his. Callie asks why things cannot just be about love. Hearing Clel’s rejection of the marriage, Sarny accidentally drops the plate of food, and she is punished when Clel forces Callie to slap the girl. That night, Delie tells Sarny to behave, otherwise she will have to do the hard labor out in the fields. Sarny replies that one day she is going to own Mr. Waller.
The next day, Callie tells Sarny to take a letter to the doctor’s place. On the way, she sees a slave trader, Tom, herding black slaves toward the Waller household. At the doctor’s house, the doctor asks Sarny to take a letter to Callie, but to keep it a secret from Clel. He then gives Sarny a penny for her troubles. Back at the plantation, Tom is willing to sell a slave to Clel for 500 dollars. Clel then questions Tom about why he is willing to sell a slave worth $3000 for only $500, wondering if the slave is a troublemaker. Clel then asks the slave to take off his shirt, revealing many scars from being whipped. Clel says that instead, he will buy the man off of Tom for only 50 dollars.
That night, while asking for tobacco, the slave begins to talk to Sarny. He tells her that he can trade her letters for tobacco, meaning he can teach her to read. He explains that she has to learn the alphabet before she learns to read and that each letter has a different meaning and shows her the letter ‘A’. She then introduces herself to the slave and the slave says that his name is ‘John’. Sarny then starts to read the letter ‘A’ in the letters between the doctor and Callie that she delivers.
The next morning, Outlaw is being punished because he snuck out the previous night to see Egypt. As Mr. Waller is about to whip Outlaw, Jeffrey, Clel’s son, asks him to stop because they are friends. Clel says ironically to Jeffrey that the slaves were made to pick his cotton instead of being his friend. Outlaw is then whipped. In Sarny's narration of the story, she states that Clel watched everyone instead of the one person he needed to watch, the mistress, his wife.
That night when the Wallers are having a party, Delie walks in on John teaching Sarny the alphabet and is outraged. She questions John about the scars on his back, and he says that they were because he had tried to run away twice. The third time, however, he successfully got away to the North but ended up coming back in order to teach slaves how to read. Delie prohibits John from teaching Sarny to read because she does not want anyone to be whipped. John agrees but says that Delie is teaching Sarny something worse: to be afraid. Sarny states that she will just learn how to read by herself.
Seeing Callie refuse an invitation from the doctor, Sarny suggests that her mistress takes both her and Homer along with her. She convinces Callie that she can watch the boy so no one would get mad. When the slaves come home from work, they find a cake on the table and accuse Sarny of stealing it. She states that Callie gave it to her but also that she did steal something. She reveals that she had stolen Homer’s alphabet blocks, which angers Old Man. Old Man says that he is willing to turn whoever is teaching letters in because Clel would kill them if he found out. He says that words are nothing, which causes John to shout that words are freedom. He explains that the white folks keep the words to themselves and that if the slaves had words, they would be free. Outlaw then asks Old Man what he knows about words to which Old Man responds by reciting the alphabet and then showing that it had cost him a finger. Later that night, John writes Sarny’s name in the dirt saying that the letters meant herself. Sarny then questions John about reading the paper, asking him how he knows that he is reading and not just making up stories.
The next day, Clel recruits everyone in his family to help with picking cotton from the fields. He promises a feast to everyone if they are successful with the crop. While Sarny and Homer are playing, she stumbles across Clel’s record book and tries to read it, but she cannot. There are "other letters" that John has not taught her. This makes her angry at John accusing him of not teaching her the entire alphabet. He explains to her that those are instead numbers and that he will never lie to her and will teach her everything he knows. Delie then agrees to learn as well. While they are at church, Sarny is overcome with tears because she is able to read the bible prompting the priest to baptize her.
After being baptized, it is revealed that Sarny had stolen a bible that Jeffrey was supposed to take care of which gets him in trouble from his father. She discovers that she had been lied to and that God was on the slave’s side. As Sarny begins to read more and more, the rest of the slaves reject it and tell her to stop. She begins to read a story in the Gazette newspaper about a slave insurrection (Nat Turner's and his army of slaves), capturing the other slaves’ attention. Sarny then tricks Homer into playing hide and seek so she can go back and read Clel's record book. The Waller plantation had a good crop of cotton this year and as promised, Clel throws a feast. The slaves use this opportunity to let Outlaw and Egypt get married.
It is discovered later that Egypt is pregnant and is forced to run away. John forges Clel’s signature for Outlaw and his wife so they can escape. In doing so, Jeffrey comes into the slaves’ house to thank Outlaw for helping out with his father, but then discovers the stolen bible. Having his feeling hurt, Jeffrey questions the slaves about who had taken the bible and Delie takes the blame for Sarny. Having told his father, Clel tries to figure out who had taken the bible because he knows that Delie did not know how to read. With no one confessing, he then tells his son to whip Delie. Reluctant at first, Jeffrey is overcome with anger and whips Delie once. As he tries to continue, he is stopped by John who says that he was the one who took it. This results in Clel chopping off John’s fingers as punishment. When asked if he had learned his lesson, John says yes but then begins to write the alphabet in the dirt. Clel then attempts to shoot John, but Jeffrey hits him in the neck with a gun instead, telling his father that he will take care of it. He tells Joe, the overseer, to sell John and get him off his property. As he is leaving, John tells Sarny "when you loose one hand, the other gets stronger", meaning that she knows what she must do now which is to forge the other note and teach other slaves how to read. When he leaves, Old man asks Sarny what John had written in the dirt, and Sarny replies that he had written “John”. Sarny is then seen forging the second note for Outlaw and telling them to name their baby John if it was a boy.
The next morning, when Sarny goes to deliver the book back to the doctor, instead of putting it on the table, she puts it in its right spot on the shelf. She then hands the pennies back to the doctor saying that she cannot keep his secrets anymore. Confused, the doctor then realizes what Sarny had meant when he realizes that Sarny had put the book in the right place. The doctor then hurries to the church where Clel and his men are also going. Clel interrupts the service saying that he has found two notes written and signed with his name in two different handwritings. He states that the first slave has been sold and is now looking for the second. When no one answers, Clel says that he will shoot all of his slaves. As he starts to count to three, Sarny finishes it saying “3”. She then says that Clel would not shoot them because they are worth money. Since Clel had lost everything in the cotton fields, the slaves are now his wealth. Sarny explains to Clel that she is worth the most to him because of what she knows. Sarny tells Callie to say what she has to say to Clel, but Callie insists that she does not know what Sarny is talking about and tells Clel to shoot the girl. Clel refuses saying that he wants to know what Sarny is talking about. The doctor then intervenes saying that he is to blame. He lies and says that he taught Egypt how to read simple things. Thinking everything has been solved, Callie tells Clel that she wants Sarny to be sold. Sarny is finally sold, and as she narrates, she explains that the story is about her and Nightjohn and that there is a bit of John in all of the slaves.Allison Jones as Sarny – taken care of by Delie after her mother was sold.
Carl Lumbly as John - Slave bought by Clel who had escaped to the North, but had given freedom up so he can teach slaves how to read.
Lorraine Toussaint as Delie – acts like a mother to Sarny and is initially against learning how to read.
Bill Cobbs as Old Man – the oldest member of the slaves who is respected by everyone.
Beau Bridges as Clel Waller – cold-hearted owner of the slaves and a cotton plantation.
Kathleen York as Callie Waller – Clel’s wife who has an affair with the doctor. She is seen as being kind and sympathetic to the slaves.
Gabriel Casseus as Outlaw – a slave who had fallen in love with a girl from another plantation.
Monica Ford as Egypt – Outlaw's love interest.
John P. Ford III as Jeffrey Waller – Clel’s oldest son who sees the slaves as friends.
Filmed on location in Gable, South Carolina at Rip Raps plantation, Nightjohn is a movie that depicts the lives of African American slaves in the antebellum South. Literacy plays an important part in the struggle for power between the slaves and their masters. The idea of keeping slaves illiterate was a tool for white Southerners to keep the slaves subordinate. Without the ability to read, slaves were often tricked into doing things that they did not want to do. They weren’t able to read the laws or deeds that affected their future and resulted in them becoming slaves. After the civil war had ended, there was a problem pertaining to what to do for the African American people. With slavery’s stabilizing influence gone, the Freedmen's Bureau was created to remedy the situation. It proposed that they should educate the former slaves and advance the reconciliation between the North and the South. They also hoped that it would create a lasting peace and order between the different races. The bureau also sought to create schoolhouses in order to regain the stability lost by the end of slavery.