What does Macbeth plan to do with Banquo and Fleance?

In William Shakespeare’s tragedy "Macbeth," Macbeth plans to have both Banquo and his son, Fleance, killed. He fears that the witches’ prophecy that Banquo’s descendants would inherit the Scottish throne will come true, threatening his own power. Macbeth believes that if he can prevent Banquo's lineage from ascending to the throne, he could secure his own position. Macbeth becomes paranoid and feels that Banquo might suspect him of foul play in Duncan's death. To maintain his grip on the throne and to attempt to prevent the prophecy from coming true, Macbeth hires two murderers to kill Banquo and Fleance. The plan is to ambush them on their way to a feast at Macbeth's castle.

However, the plan only partially succeeds. The murderers manage to kill Banquo, but Fleance escapes into the darkness, preserving the possibility of Banquo’s heirs eventually ruling Scotland, as the witches prophesied.