In the theater, people apparently don't call Shakespeare's "Macbeth" by its actual name -- it's usually called "MacB" or "The Scottish Play." The dark superstitions that hover around this play really show its power: it's a harrowing portrait of a weak man who spirals into a personal hell of ambition, murder and madness.
Shortly after a victory in battle, Macbeth and his friend Banquo are traveling home across a heath when they encounter three witches -- who greet him with "All hail, Macbeth! hail to thee, Thane of Cawdor! All hail, Macbeth! that shalt be king hereafter!"
When MacBeth is made Thane of Cawdor, he naturally begins to think that being king might be next in line. And when King Duncan visits his castle, Lady MacBeth goads her husband into murdering the king and framing a couple of innocent servants for the deed. As the witches predicted, MacBeth becomes king of Scotland.
But the witches also prophesied that Banquo would be the father of kings, so MacBeth starts tying off loose ends by hiring assassins to kill Banquo and his young son, as well as a wily thane named MacDuff and all of his family. But though MacBeth believes himself to be safe from everyone, his fear begins to grow as madness and guilt torment him and his wife...
One of the most fascinating things about "Macbeth" is how evil it is -- mass murder, insanity, bloody ghosts, a trio of manipulative witches pulling MacBeth's strings, and a nice if weak man who becomes a raving murderous paranoiac. Shakespeare starts the story on a dark note, and it gets darker and bloodier as the story winds on to its bleak climax.
In fact, the entire story is a two-part spiral -- things get tighter and more intense, even as MacBeth and Lady M. get crazier and more violent. Shakespeare litters the story with brutally intense scenes (Banquo's ghost crashing the dinner, Lady M. trying to scrub her hands clean) and powerful dialogue ("Shake off this downy sleep, death's counterfeit,/And look on death itself! up, up, and see/The great doom's image!").
The one flaw: Shakespeare's handling of the "no man born of woman" prediction is a bit lame. I mean, didn't that count as "born" back in Elizabethan times too?
Honestly, MacBeth is both a fascinating and repulsive character. He starts off as a nice ordinary thane with no particular ambition, but his weakness and his wife drive him to some pretty horrible acts. Before long, he's become somebody you desperately want to see diced into little pieces. And Lady Macbeth is little better, although there's a slight disparity between her ruthless ambition and her later insanity.
"MacBeth" is a story filled with stormy darkness and all-consuming fire -- a powerful depiction of evil and how easily we can be seduced. Just don't say its name in the theater.