The witches prophesy that Macbeth will be king, among other things.
Characters: 
First Witch

The first of a trio of mysterious "weird sisters" with the power of prophecy.

Second Witch

The second of a trio of mysterious "weird sisters" with the power of prophecy.

Third Witch

The third of a trio of mysterious "weird sisters" with the power of prophecy.

Macbeth

Thane of Glamis and a general in Duncan’s army. He is returning home from a successful battle.

Banquo

A general in Duncan’s army and friend of Macbeth. He is returning home from a successful battle.

Ross

A Scottish lord who often acts as messenger. He greets Macbeth and Banquo and bestows Macbeth with the title of Thane of Cawdor.

Angus

A Scottish lord and soldier.

Scene Summary: 

Cue thunder. The witches are back, and they finally get to meet Macbeth, who’s got Banquo in tow. The witches greet a rather bewildered Macbeth as the “Thane of Glamis,” “Thane of Cawdor,” and “king hereafter.” Since he was, in fact, the Thane of Glamis, and he’s about to become the Thane of Cawdor, we can’t help but wonder if “king hereafter” might hold some water as well. Banquo wants to know if they’re telling the truth — and he wants to know what lies ahead in his future, too. The three witches tell Banquo that his descendants will be kings, but he won’t. As they start to leave, Macbeth begs them to stay, wanting to know more about their prophecies, but the witches are already gone.

Macbeth and Banquo are busy marveling over the mysterious witches when Ross and Angus arrive to tell Macbeth that the king wants him. Ross tells him he’s about to become the Thane of Cawdor (so the witches were onto something), because the previous thane is now a traitor. Macbeth and Banquo are starting to wonder if there really might be something to the witches’ prophecies. But Banquo’s a little worried, too: couldn’t the witches be agents of evil, sent to lead them to their own demise? Maybe. But Macbeth, muttering to himself, begins to imagine that he actually could become king. There’s just one problem: to make that happen, he’d have to murder Duncan, and he can’t help but envision how he might pull that off. While Macbeth wanders around in a haze, Banquo makes excuses for his war buddy until Macbeth finally snaps out of it, and they all head off to meet the king.