In Shakespeare's "Macbeth," who helps Macbeth devise the plan to kill King Duncan?

Explanation

Banquo is a nobleman and friend of Macbeth but does not participate in the murder plot. Macduff is loyal to Duncan and opposes Macbeth. Malcolm is Duncan's son and heir, not involved in the murder plan. Lady Macbeth is the one who encourages and assists Macbeth in plotting Duncan's assassination.