In Act IV, Scene 3, it is this very fear of the evil of power and its effects that Malcolm exhibits in his distrust of the motives of Macduff who has come to England to seek Malcolm's help in restoring the rightful ruler to Scotland. For, he wonders if Macduff is a paid agent of Macbeth; he questions Macduff as a result and feigns corruption in himself in order to elicit Macduff's true feelings. When Macduff exclaims, "O, Scotland!" Malcolm realizes that the man loves his country and is loyal, so he tell Macduff the truth about himself.
By this time Macbeth senses that the witches' prediction are legitimate, however he feels a disastrous downfall. He perceives this way because he assumed to become king promptly. His high expectations were destroyed. The King's son, Malcolm was appointed heir to the throne. Malcolm had got into the way of Macbeth's ambition to be king. Which shows In act 1 scene 7 when Macbeth is thinking about killing King Duncan he talks about his 'vaulting ambition' in lines 27 - 28: "Vaulting ambition which o'er leaps itself and falls on th'otherâ€¦"/" The Prince of Cumberland, that is a step On which I must fall or else o'er leap". What Macbeth means in this quotation is that his excessive ambition is like a horse that tries to jump too high and falls on the other side of the fence. Macbeth may realise that killing Duncan may be a bit far-fetched and his plan will not work - the audience will find out what he has done if he is to go through with the murder. The second quote shows that, Macbeth already sees Duncan's son as an obstacle to his destiny. Ominously, Macbeth adds "Stars, hid your fires! Let not light see my black and deep desires;" Moreover, this shows how eager Macbeth is to hide his dark and bloody desires and give a face of pleasances.