Moist von Lipwig, who after years of undertaking confidence tricks on others finds himself caught by the guards, is sentenced to death under the alias of Arthur Spangler. After a brief spell in prison he is hung by the neck, but not killed. He is brought before Patrician Havelock Vetinari who insists that he either becomes the new Postmaster or be executed.

Moist van Lipwig learns that the Post Office has been superseded by telegraph towers known as "Clacks" which are run by the unscrupulous Reacher Gilt. In an effort to compete, Moist challenges Gilt to a race.