Tonight we hold a solemn supper and request your presence.
Act 3 Scene 2
'Tis safer to be which we destroy. Than by destruction dwell in doubtful joy.
Act 3 Scene 3
Macbeth´s prophecy came true about him being king, but now Banquo suspects him of how he was able to achieve the title of king. Since Macbeth´s prophecy came true they both think Banquo´s children are going to become king someday. So King Macbeth plans on hiring 3 murders to kill Banquo so that prophecy doesn´t happen.
Banquo and Fleance are invited to have a feast with King Macbeth and Lady Macbeth. Lady Macbeth planned to lure Banquo into false security and feel safe so he can be murdered alongside with Fleance by the 3 murders Macbeth had hired earlier.
Plan backfired and only Banquo had died, Fleance managed to escape. While they were all alone in the room with just themselves somehow Fleance managed to escape.