One of the cleverest aspects of Wicked is Gregory Maguire's story. Audiences are so familiar with L Frank Baum's source material - or rather, the 1939 film adaptation of it - that much character introduction can be dispensed of because the audience already knows who almost everybody is (or is going to be).
And that's where the beauty of the narrative shines brightest - Wicked starts out as a prequel to The Wizard of Oz, then the narrative overlaps with that of the film, and by the end it's running concurrently with it. The ease with which the story on the stage enhances and expands the audience's established knowledge is masterful, and it's a delight to join up the dots. It's the joy of being able to pause the film and say: "Meanwhile, over there..."
