Two important events take place before the opening action of the play. First, Abigail has an affair with John Proctor and is fired from her job as a housekeeper in Proctor's home.
This leads to some of the greatest tension in the play as John Proctor is forced to face his past mistakes, to defend his wife against Abigail's jealousy, and to finally admit to his affair with Abigail.
Also, the context for the accusations of witchcraft is provided by the action preceding the opening of the play wherein Abigail, Betty Parris and other girls from Salem are discovered dancing naked in the woods. Tituba is with them and they drink blood while dancing.
The act is thoroughly taboo in the town and the girls expect severe repurcussions. To deflect the town's attention, the girls begin to make accusations against towns people claiming that witchcraft is afoot in Salem.
Abigail, Betty and the girls were caught dancing in the woods by Reverend Parris. He says he saw a pot and something was moving in it. He also claims to have seen someone naked. It turns out that it was Mercy Lewis, "a sly, merciless girl" who is also heavy.