During the ball, Macbeth's intentions are to ensure that his three murders for hire take the lives of Banquo and his son Fleance. The murders ultimately fail, Fleance flees the city, and Macbeth becomes furious. As long as Fleance is alive, Macbeth fears that his power will remain precarious. He visits the witches in the cave, after having frightening visions of ghosts and dreads. When he visits the witches, they tell him that he should be wary of Macduff, a Scottish nobleman who opposed Macbeth's accession to the throne. The witches also tell him that Macduff is incapable of being harmed by a man born of woman and that he will be safe until Birnam Wood comes to Dusinane Castle. This makes Macbeth feel less uncertain about the situation..