This is one of those eternal struggles... how to boil a 100,000 word novel into a sentence or two. Check out his post - and the story of how he got Janet Reid to represent him. Yes, Janet Reid. THE Janet Reid.
The closest I've been able to get so far is this:
"A Ranger and a lady's maid try to stop a renegade prince with magical powers from murdering his older brother in order to gain the kingdom for himself."
P.S. After I posted this, I turned on the TV and looked up a few movie blurbs on the cable guide. Here are a couple of examples:
Monsters Vs. Aliens - After being struck by a meteorite, a woman develops a unique ability and is taken to a secret underground facility where she meets a group of monsters and is later commissioned by the President to ward off evil aliens attacking the planet.
City of Ember - A generator that has been providing power to an underground city for 200 years is beginning to fail as two teenagers try to discover clues about their city's existence so they can find a way out, but the mayor wants things to keep things the way they are.
So mine seems a little too lean.
How about this?
The Golden Gryphon - An emotionally-repressed Ranger and a shy young gentlewoman try to stop a renegade prince with magical powers from murdering his older brother and gaining control of the kingdom