With the help of Eric, a fourteen-year-old demonologist and Rincewind, the disc's worst wizard, Terry Pratchett explains: 
 * why all roads lead to hell, 
 * that it's the road from hell that is paved with good intentions, and 
 * how wishes always give you exactly what you want in exactly the way you don't want it. 
 Along the way, there is treasure, the most beautiful woman, and the beginning of time. And (view spoiler)[Rincewind Lives! (hide spoiler)]