At the beginning of the act, whose murder is macbeth planning and why?

The correct answer to this open question is the following.

At the beginning of the act, Macbeth is planning the murder of Banquo and his son Fleance due to a prediction of the witches that predict that Banquo's heirs would become kings, and Macbeth felt threatened.

In that act 3 of the lay, Macbeth is preparing to go to war because Mcduff and Malcolm want to fight him and are making preparations. Back in the murder scene, murderers fight against Banquo and killed him but his son survives.

"The Tragedy of Macbeth" is a famous play written by English author William Shakespeare in 1606 that refers to the internal struggle of Macbeth and his addiction to power and control.