"Pyramids"--His daddy was a mummy
Teppic, prince of a country that closely resembles Ancient Egypt has been sent to Ankh-Morpork to be trained as an assassin. This is a practical career choice for someone who will one day reign as Pharaoh in the desert kingdom of Djelibeybi.
News of the old Pharaoh's death arrives in Ankh-Morpork via magical phenomena such as vegetation sprouting wherever Teppic steps. He makes his way back to Djelibeybi, filled with new-fangled ideas on how to move his country out of the Millennium of the Pyramid and into the Century of the Fruit Bat.
But the pyramids themselves are formidable enemies to progress. They trap time. Prince Teppic's father is dead, but he is still sentient and horribly aware that he is being turned into a mummy. He has high hopes that his son will end all of this death-worshiping nonsense, but Teppic is guilt-tripped by the high priest into building his father the biggest pyramid of all.
When the young king finally realizes that the mad, old high priest is the real ruler of Djelibeybi, he dons his black assassin's outfit and sets about rescuing beautiful handmaidens, thwarting the sacred crocodiles and their priests, and confronting Djelibeybi's ancient animal-headed gods.
Not bad for a kid who started out by letting the grass grow under his feet.
This is ancient Egypt and Classical Greece as seen through the eyes of a mathematical genius who happens to be a camel, a young assassin who happens to be a king, and a mummy who would rather not spend the rest of his afterlife in Discworld's biggest pyramid.
"Small Gods"--How Om got his believers back
The Great God Om wakes up in tortoise-form just as an eagle hurls him into a compost pile. If you're the type of person who worries about being struck by lightning while reading the wrong kind of book, stay away from "Small Gods." Terry Pratchett blasphemes against (or maybe I should say 'explains') religion in this book, and most philosophies too. This is one of his more seriously comic Discworld books, although only Pratchett (and Monty Python) would even consider an attempt at a comedy about the Grand Inquisition
If Galileo had muttered, "Eppur si muove!" to the Inquisition on Discworld, he no doubt would have been referring to the gigantic turtle that carries the world on its back. He would have burned too, old as he was, if Vorbis the exquisitor had overheard him blaspheming against the perfect sphere of Discworld, which orbits around the Sun "as Man orbits the central truth of Om."
Meanwhile Om scrabbles out of the compost heap and discovers Brutha, a young novice who is hoeing melons in the temple garden. Brutha is the only person left on Discworld who truly believes in Om, and really bad things happen to gods who lose all of their believers.
However, Brutha almost loses his god. Vorbis the exquisitor discovers the small tortoise hissing at him and doesn't recognize it as his God, Om. He flips it over, inserts a couple of pebbles into its shell so it can't right itself, then sticks Om on the garden wall to broil in the sun.
Vorbis is a bad 'un.
After this temporary setback (setback, get it?), "Small Gods" carries on with the tale of Om and Brutha and their adventures as Om tries to figure out why he ended up as a tortoise, and Brutha attempts to discover truth in religion. This book is a work of fiction. All the characters and events portrayed in this book are fictional, and any resemblance to real people or incidents is purely coincidental. However if you read very carefully, you may spot coincidental resemblances to Tomás de Torquemada, Jesus, any number of classical Greek philosophers, early Christian saints, Old Testament prophets, and Galileo Galilei.
"Hogfather"--It's beginning to look a lot like Christmas
Up on the housetops porkers paw...at least on Discworld they do. And down the chimney comes good old Hogfather. Or at least, he's supposed to. Who can take his place if the Hogfather is somehow...indisposed? How about Death and his chain-smoking cook, Albert? Yes, Virginia, we really are on Discworld.
"Hogfather" is one of my favorite Discworld novels (and the made-for-TV movie isn't bad, either) because only Pratchett has the audacity to tangle together three of our favorite anthropomorphic personifications (Santa Claus a.k.a. the Hogfather, the Tooth Fairy, and Death) in one intricate story line that is really about belief and what makes the Sun come up in the morning.
Only Death's granddaughter, Susan has the moxie and the common sense to sort out new anthropomorphic personifications (how about a god of hangovers, and a Verruca gnome) that rush into the belief vacuum created by the absence of Hogfather, thwart the evil Auditors, and foil the assassin who has broken into the Tooth Fairy's castle. Meanwhile her Granddad is delivering some very interesting presents to the little kiddies of Discworld.
On Gouger! On Tusker! On Rooter and Snouter!