In act 4 of Arthur Miller's play, The Crucible, a fictionalized dramatization of the Salem witch trials of 1692, Reverend Samuel Parris tells Deputy Governor Danforth, who was presiding over the trials, that Parris's niece, Abigail Williams, "has vanished." Rev. Parris tells Danforth that his daughter, Betty, told him that she heard Abigail and Mercy Lewis talking about ships the week before, and both Abigail and Mercy have now been missing for three days. Rev. Parris adds that just this evening, he also discovered that his "strongbox is broken into," and that the entirety of his life savings is gone, implying that Abigail and Mercy took his money when they left Salem.
Danforth offers to send a search party for Abigail and Mercy, but Rev. Parris says that they are probably already aboard a ship and therefore are unlikely to be found.
Rev. Parris offers a possible explanation as to why Abigail and Mercy might have run away.
PARRIS. I cannot think they would run off except they fear to keep in Salem anymore—since the news of Andover has broken here.
In a dramatic scene during the trial, John Proctor accuses Abigail of committing adultery with him. This is reason enough for Abigail to want to leave Salem: she wants to escape being ostracized for her illicit relationship with Proctor and to avoid the constant knowing, judgmental looks she's likely to receive from the community for the rest of the time she lives in Salem.
Abigail and Mercy were also complicit in accusing a number of people of witchcraft, and Abigail was guilty of sending innocent Salem residents to their deaths. Neither Abigail nor Mercy had yet been accused of any crimes related to their false testimony at the trials, but they might have decided that it was better for them to leave Salem before they became the subjects of trial proceedings themselves.
Rev. Parris mentions "the news of Andover," which refers to witch trials in Andover, Massachusetts, about fifteen miles northwest of Salem. Over forty Andover residents were accused of witchcraft, in much the same way as in Salem, and three of the accused were executed before the people of Andover rose up and brought an end to the witch trials. News of the uprising had apparently reached Salem, and this might be another reason that Abigail and Mercy decided to leave Salem, before they were caught up in an anti-witch trial movement in Salem.
In The Crucible, Arthur Miller portrays Abigail Williams as about seventeen years old and as a servant in the Proctor household, who has an affair with John Proctor. Abigail accuses John's wife, Elizabeth, of witchcraft so that she can marry John after Elizabeth is executed as a witch.
The real Abigail Williams was a girl of about eleven or twelve who lived with her uncle, Reverend Samuel Parris, and his family, possibly because Abigail's parents had died.
After Abigail's testimony on June 3, 1692, the day that John Willard and Rebecca Nurse were formally accused of witchcraft, Abigail Williams disappears from the historical record.
The Salem Witch Museum website offers this observation:
Even though Abigail played a major role as an accuser at the beginning of the trials, especially in March, April, and May, she gave her last testimony on June 3rd 1692. There is no historical documentation suggesting why Abigail virtually disappeared from the court hearings. In addition, there are no records indicating what happened to Abigail after the events of 1692. It is suggested that she never married and died a single woman, but without any evidence we will never be quite certain.