Terry Pratchett's The Colour of Magic

The Colour of Magic (1x1)

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Constantly failing at the Unseen University, the wizard Rincewind is given the task by the Patrician of looking after the Discworld's first tourist: Twoflower. The main character is the incompetent and cynical wizard Rincewind, who involuntarily finds himself as a guide to the naive tourist, Twoflower. After they are forced to flee from the city of Ankh-Morpork after a terrible fire they are sent on a journey across the disc which is unknowingly being controlled by a board game being played by the Gods. They meet two barbarians on their way out of morpork, Bravd and Weasel. After their visit to Wyrmberg, the upside-down mountain which is home to dragons that only exist in the imagination, their journey leads them to the country of Krull, perched on the very edge of the Discworld where they are thrown off the edge of the Disc due to the Krullian's urge to find out the gender of Great A'Tuin (the turtle which is swimming through space with four elephants resting the Disc on top).