Act 3 of Macbeth is a pivotal point in the play, where the plot takes a dark turn. Here is a summary of what happens in each scene:

• Scene 1: Banquo voices his suspicions that Macbeth has killed Duncan in order to fulfill the witches prophecies. Macbeth and Lady Macbeth enter, and Macbeth invites Banquo to a feast that night. Banquo accepts and plans to go for a ride in the afternoon. Macbeth mentions that they should discuss the problem of Malcolm and Donalbain, who have fled from Scotland and may be plotting against his crown. After Banquo departs, Macbeth is left alone and summons the two murderers he has hired. He voices his greatest worry of the moment, that the witches prophecy will also come true for Banquo, making his children kings. He hires the two men to kill Banquo and Fleance.

• Scene 2: The murderers kill Banquo, who dies urging his son to flee and to avenge his death. One of the murderers extinguishes the torch, and in the darkness, Fleance escapes.

• Scene 3: At a banquet in the royal palace at Forres, Macbeth sees Banquos ghost sitting in his chair. Lady Macbeth makes excuses for her husband, saying that he occasionally has such "visions" and that the guests should simply ignore his behavior. The ghost disappears, and Macbeth recovers, telling his company that he has a strange infirmity which is nothing to those that know him. As he offers a toast to the company, however, Banquos specter reappears and shocks Macbeth into further reckless outbursts.

In summary, Act 3 of Macbeth is where Macbeth hires murderers to kill Banquo and Fleance, and Banquos ghost appears at a banquet, causing Macbeth to behave erratically.