This powerful act ends with Mary Warren rejoining the girls by testifying against John Proctor and with John Proctor seemingly confessing himself to be in league with Satan. What is particularly powerful about this Act is the way that the girls eerily echo every word that Mary Warren says, whilst pretending to be enchanted by her. The scream that they all utter as the "bird" of Mary Warren's spirit descends on them is truly terrifying. However, what is far more shocking is Proctor's final speech, which he utters as he "laughs insanely":
A fire, a fire is burning! I hear the boot of Lucifer, I see his filthy face! And it is my face, and yours, Danforth!
Such a dramatic speech accompanied by such laughter clearly is a massive change from the sober and respectable figure that John Proctor is presented as being up until this point. His words are treated as a clear confession of consorting with Satan by Danforth, and even though Hale at the same time as Proctor is taken to jail shows that he completely disbelieves what has happened, his cries are not heard. Evil is shown to have triumphed, and this is above all what makes the end of this Act so dramatic.