Macbeth gives another soliloquy, in which he is mad and frustrated because Banquo's children are supposed to become kings. He instructs murderers to kill Banquo and Fleance, and to make sure that it's done off of castle grounds.
The murderers attempt to kill Banquo and Fleance in the night. They succeed in killing Banquo, but Fleance flees.
Macbeth refuses to sit at the table, as he sees the ghost of Banquo sitting in his seat, and begins to "throw a fit". Lady Macbeth sends all of the guests home as a result of Macbeth's "fit" not ending.
Macbeth is mad at Macduff and suspicious as to why he did not attend his coronation. Macbeth says that he will go to speak with the witches to figure things out
Hecate, the goddess of witchcraft, does not like Macbeth, as his intentions are selfish and he only cares for himself. She plans to give him too much information to overwhelm him to kill himself.
Lennox is informed that Duncan died, Macbeth took his place as king, Banquo died, Fleance fled, and suspicion of Malcolm and Donnalbain.