Source plot synopsis — includes the ending
The Night Watch, which is generally seen as incompetent, starts to change with the arrival of idealistic new recruit Carrot Ironfoundersson, a human orphan raised by dwarfvish parents. When the Librarian of the Unseen University reports a book of magic stolen, Sam Vimes, Captain of the Night Watch, links the theft to the dragon's appearances. The Watch's investigation makes the acquaintance of Lady Sybil Ramkin, who breeds small swamp dragons, and gives an underdeveloped dragon named Errol to the Watch as a pet.
At first, the plot works flawlessly. The Patrician is ousted in favour of the new king, but the banished dragon returns and makes itself king, demanding gold and virgin sacrifices (for it to eat), and prepares to wage war against Ankh-Morpork's neighbours for the further acquisition of its hoard. The dragon puts the Patrician's secretary Lupine Wonse as its mouthpiece against his will.
Vimes confronts Wonse, having figured out that he is the Supreme Grand Master, and responsible for the dragon's appearance. Wonse has the palace guards imprison Vimes in the same cell as the Patrician. Vimes escapes with the help of the Librarian and runs to rescue Sybil, chosen as the first sacrificed maiden. After the remaining Watch fail to kill the king through a 'million-to-one chance' arrowshot, Errol fights it, and knocks it from the sky. The assembled crowd closes in to kill it, and Sybil pleads for the dragon's life. Carrot arrests it, but Errol lets it escape with him. They find out that the dragon is in fact female, and the battle between them was a courtship ritual.
Vimes arrests Wonse, as he tries to summon another dragon, telling Carrot to "throw the book at him". Wonse falls to his death after the very literal Carrot hits him with a thrown copy of Laws and Ordinances of Ankh-Morpork.
The Patrician is reinstated as ruler of Ankh-Morpork, and offers the Watch anything they want as a reward. To everyone's surprise, they ask only for a modest pay raise, a new tea kettle, and reluctantly, a dartboard.
Sources and content license
Source and revision history ↗ · Adapted from Wikipedia contributors, Guards! Guards!. Section headings and formatting adjusted. · Content license