Our narrator, Korvas, is doing a sideshow talk to a crowd and trying to part them from their money to hear his story. He's a former cheating carpet merchant, obnoxious, hypocritical, a boaster, and many other things besides ... but he's a self-aware and intelligent obnoxious boaster and he has one hell of a story to tell. You see, Korvas has inherited (from someone he didn't know, which kind of surprises him) a small box with four drawers. These drawers provide him with things: rarely ever things he wants, but always things he needs - even though he often doesn't see it that way. The box may contain the power of the gods, or it may be a god ... in any case, it's going to take him for a hell of a trip whether he wants to go or not.
The story doesn't go beyond the relatively common fantasy quest format as Korvas tries to figure out how to A) save himself, and B) save the world, but it's a fairly unusual quest with an entertaining narrator, and I found it a fast and very enjoyable read.