A Scottish general learns from three witches that he will rise to great power, and with his wife's encouragement he murders the reigning king to seize the throne. Haunted by guilt and fear, the couple descend into paranoia, hallucinations, and ruthless violence, while supernatural prophecies and apparitions complicate their choices. Banquet scenes and sleepwalking episodes dramatize moral disintegration, as opposing nobles and bereaved leaders gather resistance. The plot culminates in a military confrontation that restores order and punishes tyranny. Themes include ambition and its corrosive effects, the tension of fate versus agency, and the instability of appearance versus reality.