Summary of the summary: Macbeth has agreed to kill King Duncan. He sees an imaginary dagger in the air that leads him to the king's room. He stabs King Duncan in his bed.
Macduff, the quiet hero, arrives to accompany King Duncan on his day's journey. Macduff discovers the king has been murdered and he wakes up all the thanes (generals) and royals who are sleeping at Macbeth's castle.
In the confusion, Macbeth kills the 2 drugged servants who were guarding the king. He wants everyone to think that the servants were paid to kill the king.
King Duncan's sons run away because they think they could be killed next.
The following day, Macduff goes back to his castle. He doesn't watch the ceremony when Macbeth is crowned King of Scotland.