Act III begins with a detailed description of an anteroom outside the court. The audience hears the voices of Judge Hathorne and Martha Corey, who is on trial for being a witch, carry from the courtroom.

The judge is questioning Martha about the supposed suspicious activities that have led her to be accused as a witch. As revealed in the previous act, many town members have been accused, and the proceedings are devolving into hysteria.

During Martha's testimony, she remains adamant that she has not hurt the girls who have been making accusations, and her husband, Giles Corey, claims to have evidence proving her innocence. He says that "Thomas Putnam is reaching out for land," which is why his daughter Ruth has accused Martha.

Giles, clearly agitated about his wife's possible execution, is thrown out of the courtroom. Danforth, the deputy governor, enters and asks Corey how he imagines his outburst will help his wife's cause. Giles explains that he told the court his wife was reading books but never said she was a witch. Danforth instructs Giles to follow the appropriate legal procedures if he wants to enter evidence in favor of his wife, and Giles is taken away.

Next, Francis Nurse enters to plead for his wife, Rebecca. Danforth says he has heard only good things about Francis and is shocked to see him in "such an uproar." Francis blatantly states that "the girls are frauds" who "are all deceiving" the town. Infuriated, Judge Hathorne accuses Francis of contempt, and Danforth suggests Francis is foolish to question his judgment, as almost four hundred witches have been imprisoned and another seventy-two executed on his orders.

Mary Warren then appears, escorted by John Proctor. John tells Danforth that Mary has a signed deposition saying she never saw any spirits, but Danforth refuses to accept it. Mary then directly tells Danforth that the girls have merely been pretending, but her confession is disregarded. Instead, Danforth turns on John and questions his purpose in suggesting that the trials are a farce. Danforth speculates that John may be lying to protect his wife or, even worse, possess some darker motive for undermining the court.