I first read Wicked by Gregory McGuire in 2008 because it had fab reviews, a Broadway show and I'm a HUGE Wizard of Oz fan.
After the death of her mother, Elphaba goes off to the Emerald city for school where she is roomed with the gorgeous and spoiled Galinda. They strike up something of a friendship over the years and have a small band of strange friends.
Elphaba falls in love with the prince of the Arjiki tribe, Fiyero, who is already betrothed to another, but that does not stop them from having their own intimacies. Fiyero comes and goes from the Emerald City in his travels and is with Elphaba while in town.
Through tragedy, Elphaba travels to the Vinkus, where Fiyero is from, and meets his bitter wife, children and his wife's several sisters. This is the setting where Elphaba becomes the Witch we all know.
Wicked is a very politically charged book, with several parts that remind me or George Orwell's Animal Farm in that McGuire has both animals (like our pets and wild animals) and Animals - who walk, talk, dress and teach college. The Wizard, according to Elphaba and her constituents, is trying to turn Animals back into regular old animals. This is the basis for the Cowardly Lion character.
I reread the book this past year and still found it confusing, being way too political for my personal taste. I like the personal story of Elphaba, Galinda, Fiyero, Boq and the others much better. The book is nothing at all like the Broadway adaptation, and I found that to be much more to my personal liking.
But I have to say that I thoroughly enjoyed McGuire's writing and his weaving of the tale. If you have not read Wicked or the three books that follow (Son of a Witch, A Lion Among Men, and Out of Oz), I would recommend reading them as pieces of great literary works!