On the Discworld, "sourcerers"—wizards who are sources of magic, and thus immensely more powerful than normal wizards—were the main cause of the Great Mage Wars that left areas of the Disc uninhabitable.

There are many references to geasa in the text, which are idiosyncratic curses, vows or obligations placed upon a person (usually a hero, such as Cúchulainn in Irish mythology).

A dying wizard who flouted the rule against having children makes a bargain with Death that allows his spirit to inhabit his staff, which he passes on to his eighth son, who is born a sourcerer.

Rincewind, The Luggage and the Librarian miss Coin's arrival, having fled the University shortly beforehand after the foreboding departure of all of its magically-influenced pest populations.

The trio are eventually separated; Rincewind is thrown into the snake pit, where he meets Nijel the Destroyer, a barbarian hero in training.

They join up with Creosote and Conina, the latter immediately falling in love with Nijel, and they encounter Abrim, who had put on the Archchancellor's hat hoping to gain power from it, only to be possessed instead.

Upon hearing Creosote express anti-wizard sentiments, an angry and humiliated Rincewind abandons the group, taking the flying carpet and making his way to the University, where he learns that the Librarian has saved the library books by hiding them in the ancient Tower of Art.

The other wizards leave the tower as Rincewind rushes forward, grabbing the child and sending both of them to the Dungeon Dimensions while Death strikes the staff and takes Ipslore's soul.

"[2] A reviewer from Publishers Weekly felt that Sourcery was skillfully written, stating "Pratchett does not merely play with words, he juggles shrewd observations with aplomb."

"[4] Thomas M. Wagner from SF Reviews.net gave the book a 3.5/5 rating, commenting that the story "has Pratchett's trademark lightning pacing, and it fires gags and one-liners at you as if from a fully automatic Uzi."

He stated that though he found most of Sourcery funny, "it was very evident to me that Pratchett was, at this early stage of the series, barely scratching the surface of what his considerable wit is capable of.