Lady Macbeth is the driving force, the main planner of the plot to kill the King of Scotland, Duncan.
Explanation:
Lady Macbeth is the perfect example of ambition in the play. She embodies the qualities or characteristics that Macbeth himself is not capable of. When Macbeth first told her about the three witches' prophecy, she immediately accepts that power is meant for her husband. she did not question the witches' words nor does she seem to have any doubts. She is all for it. And whenever Macbeth wavers in his attempts, she would manipulate and question his capability, calling him weak and pushing him to agree to the murder plan. In fact, she was the one to come up with the plan to murder the king when she learned that he will be a guest in their house. She is so determined to get the throne for her husband, even suggesting that if she had been the man of the house, she would trade places with Macbeth for the throne.