Climax (Act Three of The Crucible)

Arthur Miller, the playwright of The Crucible, once said, "Betrayal is the only truth that sticks." Betrayal is a recurring theme in many works of literature. Friends or family may betray a protagonist; a protagonist may betray his or her own values.

Consider a novel, a movie, a song, or a play with which you are familiar that includes an act of betrayal. How is such a betrayal possible? What are the consequences of betrayal? Do similar acts of betrayal occur outside of fictional tales? Do they occur in real life? Could acts of betrayal similar to those in The Crucible happen in real life?