In Act I, Scene 5, Lady Macbeth receives a letter from her husband describing his encounter with the witches and their prophecy that he will become king of Scotland. She is presented as a devoted wife, willing to abandon whatever scruples she has to help her husband achieve what they view as his destiny. When she discovers King Duncan will be at their castle, she immediately resolves to "unsex" herself, becoming ruthless and cruel in order to push Macbeth, who she views as "too full of the milk of human kindness" to carry out the murder that will put him on the throne. She is also remarkably assertive. No sooner does she learn Duncan will be staying at Inverness that night then she begins to hatch a plan to kill him. She tells Macbeth what to do, advising him to greet Duncan with great hospitality so as not to reveal their plot:
bear welcome in your eye,
Your hand, your tongue; look like the innocent flower,
But be the serpent under't.
Beyond that, she tells Macbeth, he should "leave the rest to me," meaning Macbeth should simply act normal while she plans the brutal and treasonous murder of the king. Lady Macbeth's actions would have been viewed by Shakespeare's audiences as not only devious and cruel, but as an inversion of the natural order of things. This is certainly how she is presented in this scene, and it is consistent with the theme originally described by the witches: what's fair is foul and what's foul is fair. Yet the modern audience might be equally struck by Lady Macbeth's love and ambition for her husband as well as her willingness to defy prescribed gender roles. As for the potential for conflict, it is obvious the couple is plotting to kill the King, an act that will plunge Scotland into bloody chaos.