The novel posits a Victorian England where inventor Charles Babbage succeeds in his ambition to build a mechanical digital computer, his difference engine. Following this success, these massive computers have been mass-produced, and their use emulates the innovations which actually occurred during the information technology and internet revolutions. The novel explores the social consequences of having such a revolution a century before its time.
The action of the story follows a paleontologist and various other 'savants' who are on the trail of a mysterious set of reportedly very powerful computer punch cards.
In the novel, the British Empire is more powerful than in reality thanks to the power of steam driven computers. Japan is one of its colonies and the United States has broken apart into several smaller nations. Among other historical characters, the novel features Texan President Sam Houston.