I am settled, and bend up each corporal agent to this terrible feat.
The three witches meet up to discuss where they should meet up again. They decide to meet up in a open field where Macbeth will be there
Is this a dagger which I see before me, the handle toward my hand?
Macbeth (right) and Banquo (left) had just came back from a war. They were walking when they stumbled upon the three witches. The three witches prophesied their future with Macbeth being future thane of Cawdor and future king and Banquo's descendants being kings.
Currently, Duncan is at Macbeth's castle and rewarding him for his bravery in battle. He also received Thane of Cawdor as part of that reward and is seeking to become the future king with the "help" of Lady Macbeth. In this scene, Macbeth finally agrees to killing Duncan once and for all.
Fly, good Fleance, fly, fly, f...
In this scene, Macbeth sees a floating dagger in front of him, which is actually just one of his many hallucinations that he has during this play. He experiences this hallucination because of the fact that he is filled with guilt that he is about to go kill the king.
In this scene Macbeth gets manipulated by both Lady Macbeth (wanting the best for him, in this case to become king) and the witches (looking to cause evil) by killing Duncan. This is where majority of the problems arise from.
Macbeth has already become king and now he is trying to eliminate any possible threats in the way. So, he decides on hiring three murderers to kill Banquo and his son, Fleance. Banquo unfortunately dies, however Fleance does escape from them.