The Crucible, a historical play based on events of the Salem witchcraft trials, takes place in a small Puritan village in the colony of Massachusetts in 1692. The witchcraft trials, as Miller explains in a prose prologue to the play, grew out of the particular moral system of the Puritans, which promoted interference in others' affairs as well as a repressive code of conduct that frowned on any diversion from norms of behavior.
The play begins in the home of Reverend Samuel Parris, whose daughter, Betty, lays ill. Parris lives with his daughter and his seventeen-year old niece, Abigail Williams, an orphan who witnessed her parents' murder by the Indians. Parris has sent for Reverend Hale of Beverly, believing his daughter's illness stems from supernatural explanations. Betty became ill when her father discovered her dancing in the woods with Abigail, Tituba (the Parris' slave from Barbados) and several other local girls. Already there are rumors that Betty's illness is due to witchcraft, but Parris tells Abigail that he cannot admit that he found his daughter and niece dancing like heathens in the forest. Abigail says that she will admit to dancing and accept the punishment, but will not admit to witchcraft. Abigail and Parris discuss rumors about the girls: when they were dancing one of the girls was naked, and Tituba was screeching gibberish. Parris also brings up rumors that Abigail's former employer, Elizabeth Proctor, believes that Abby is immoral.
Thomas and Ann Putnam arrive and tell Parris that their daughter, Ruth, is sick. Ann Putnam admits that she sent Ruth to Tituba, for Tituba knows how to speak to the dead and could find out who murdered her seven children, each of whom died during infancy. When the adults leave, Abigail discusses Betty's illness with Mercy Lewis and Mary Warren, the servants of the Putnams and the Proctors, respectively. Abigail threatens them, warning them not to say anything more than that they danced and Tituba conjured Ruth's sisters. John Proctor arrives to find Mary and send her home. He speaks with Abigail alone, and she admits to him about the dancing. In the past, John and Abigail had an affair, which is the reason why Elizabeth Proctor fired her. Abigail propositions John, but he sternly refuses her. When Betty hears people singing psalms from outside, she begins to shriek. Reverend Parris returns, and realizes that Betty cannot bear to hear the Lord's name.
Giles Corey and Rebecca Nurse are the next to visit. The former is a contentious old man, while the latter is a well-respected old woman. Rebecca claims that Betty's illness is nothing serious, but merely a childish phase. Parris confronts Proctor because he has not been in church recently, but Proctor claims that Parris is too obsessed with damnation and never mentions God.
Reverend John Hale arrives from Beverly, a scholarly man who looks for precise signs of the supernatural. Parris tells him about the dancing and the conjuring, while Giles Corey asks if there is any significance to his wife's reading strange books. Hale questions Abigail, asking if she sold her soul to Lucifer. Finally Abigail blames Tituba, claiming that Tituba made Abigail and Betty drink blood and that Tituba sends her spirit out to make mischief. Putnam declares that Tituba must be hanged, but Hale confronts her. Upon realizing that the only way to save herself is to admit to the charge, Tituba claims that the devil came to her and promised to return her to Barbados. She says that several women were with him, including Sarah Good and Sarah Osburn, and the girls join in the chorus of accusations, name more people they claim to have seen with the devil.
The second act takes place a week later in the Proctor's home. John Proctor returns home late after a long day planting in the fields, and Elizabeth suspects that he has been in the village. Mary Warren has been there as an official of the court for the witchcraft trials, even after Elizabeth forbade her. Elizabeth tells John that she must tell Ezekiel Cheever, the constable, that Abigail admitted that Betty's sickness has nothing to do with witchcraft, but Proctor admits that nobody will believe him because he was alone with Abigail at the time. Elizabeth is disturbed by this, but Proctor reprimands her for her suspicion. Mary Warren arrives and gives Elizabeth a poppet that she made in court. Mary tells them that thirty-nine people have been arrested and Sarah Osburn will hang, but not Sarah Good, who confessed. When Proctor becomes angry at Mary, she tells him that she saved Elizabeth's life today, for her name was mentioned in court.
John Hale arrives. He tells the Proctors that Rebecca Nurse was charged, then questions Proctor on his churchgoing habits. Finally he makes Proctor state the ten commandments; he can remember nine of the ten, but Elizabeth must remind him of adultery. Proctor tells Hale what Abigail admitted about Parris discovering her in the woods, but Hale says that it must be nonsense, for so many have confessed to witchcraft. Proctor reminds him that these people would certainly confess, if denying it means that they be hanged. Hale asks Proctor whether he believes in witches, and he says that he does, but not those in Salem. Elizabeth denies all belief in witchcraft, for she believes that the devil cannot take a woman's soul if she is truly upright.
Ezekiel Cheever arrives to arrest Elizabeth on the charge that she sent her spirit out to Abigail and stuck a needle in her. Cheever finds the poppet, which has a needle in it, but Mary Warren says that she made the poppet in court that day, although Abigail witnessed her making it. Upon hearing the charge, Elizabeth claims that Abigail is a murderer who must be ripped out of the world. Proctor rips up the warrant and tells Cheever that he will not give his wife to vengeance. When Hale insists that the court is just, Proctor calls him a Pontius Pilate. He finally demands that Mary Warren come to court and testify against Abigail, but she sobs that she cannot.
The third act takes place in the vestry room of the Salem meeting house, which serves the court. Giles Corey arrives with Francis Nurse and tells Deputy Governor Danforth, who presides over the trials, that Thomas Putnam is charging people with witchcraft in order to gain their land. He also says that he meant nothing when he said that his wife read strange books.
John Proctor arrives with Mary Warren, and presents a deposition signed by Mary that asserts that she never saw any spirits. Parris thinks that they are there to overthrow the court, and Danforth questions whether Proctor has any ulterior motive, and tells Proctor that his wife is pregnant and thus will live at least one more year, even if convicted. Proctor also presents a petition signed by ninety-one people attesting to the good character of Elizabeth Proctor, Rebecca Nurse and Martha Corey. Parris claims that this is an attack upon the court, but Hale asks Parris if every defense is an attack on it.
Putnam arrives at the court, and Giles Corey charges him with murder. Giles tells Danforth that someone told him that Putnam prompted his daughter to accuse George Jacobs so that he could buy his land. Giles refuses to name this person, and so is arrested for contempt. Abigail then arrives with the other girls, and Proctor tells Danforth how Abigail means to murder his wife. Abigail pretends that she feels a sharp wind threatening her. Proctor grabs her by the hair and calls her a whore, finally admitting his affair.
Danforth orders that Elizabeth be brought to the court. If Elizabeth admits to firing Abigail for her affair, Danforth will charge Abigail with murder. Elizabeth, thinking that she is defending her husband, only claims that she fired Abigail because of poor work habits. Proctor cries out for Elizabeth to tell the truth, and Hale admits that Elizabeth's lie is a natural one to tell. Abigail then claims that Mary Warren's spirit is attacking her in the form of a bird. Although Mary claims that the girls are lying, she soon breaks down and tells Danforth that Proctor is in league with Satan and wants to pull down the court. Proctor cries out that God is dead, and that a fire is burning in Hell because the court is pulling Heaven down and raising up a whore. Hale denounces the proceedings and quits the court.
The fourth act takes places several months later in the autumn at the Salem jail cell. Cheever details how the town is in shambles because so many people are in jail. Hale has been begging Rebecca Nurse to admit to witchcraft. Parris arrives and tells Danforth how Abigail has vanished with Mercy Lewis and stolen his money. Parris worries about the rumors of rebellion against the witchcraft proceedings in Andover, but Hathorne reminds Parris how there has only been great satisfaction in all of the Salem executions. Parris reminds him that Rebecca Nurse is no immoral woman like the others executed and there will be consequences to her execution. Still, Danforth refuses to postpone any of the executions.
Danforth calls for Elizabeth Proctor, and Hale tells her that he does not want Proctor to die, for he would feel responsible for the murder. He tells Elizabeth that God may damn a liar less than a person who throws one's life away, but Elizabeth claims that this may be the Devil's argument. Finally Elizabeth agrees to speak with Proctor, who is brought in bearded and filthy. Proctor and Elizabeth discuss their children, and Elizabeth tells him how Giles Corey died: when he refused to answer yes or no to his indictment, and was thus pressed with stones until he would answer. He only gave the words "more weight" before they crushed him.
Proctor says that he cannot mount the gibbet as a saint, for it would be a fraud to claim that he has never lied. Elizabeth says that she has her own sins, for only a cold wife would prompt lechery. Finally Proctor decides that he will confess himself. Danforth demands a written confession and, to prove the purity of his soul, he demands that Proctor accuse others. Hale suggests that it is sufficient for Proctor to confess to God, but Danforth still requires a written statement. Proctor refuses, because he wishes only to keep his good name for the respectability of his children. Danforth refuses to accept his confession, and orders that he be hanged. Hale begs Elizabeth to plead with Proctor to sign a confession, but Elizabeth claims that Proctor now has his goodness, and nobody should take it away from him.