Elizabeth Proctor, John Proctor’s wife, was accused of being a witch and she was sent to prison. John wants to save her as well as the others in the community who have been falsely accused. The complication here is that one of the accusers is Abigail Williams, a teenage girl with whom John has had an affair. First he tries to bring in Mary Warren (another teenage girl) to explain to the court that the whole thing was made up. This does not work. Next John confesses to the affair with Abigail. He thinks that his confession will show that Abigail is only accusing Elizabeth because she wants her out of the way so that she can marry John. This also does not work, and John is taken to the dungeon. While he is in the dungeon, Elizabeth is sent in to try to convince John to confess in writing that the charges against him are true, but he refuses to admit to something that is a lie.
By the time Act 4 begins there are hundred of people who have been arrested. The people who are specifically mentioned as having been arrested are Elizabeth Proctor, Martha Corey, Rebecca Nurse, Tituba, Sarah Good, Goody Osburn, George Jacobs, and John Proctor. Unlike the other characters, it is John Proctor who seems to be the one accused person who is kept separate (possibly in a dungeon) away from the others.