Anti-Traction League

Mortal Engines quartet

Original cover designs for the Mortal Engines Quartet
Author	Philip Reeve
Cover artist	David Frankland, David Wyatt
Country	United Kingdom
Language	English
Genre	Science fiction Steampunk Postapocalyptic
Publisher	Scholastic
Publication date	2001–2006
Media type	Print (hardback and paperback)

Predator Cities is the title of a tetralogy, sometimes called the Predator Cities Quartet, consisting of four novels: Mortal Engines (2001), Predator's Gold (2003), Infernal Devices (2005), and A Darkling Plain (2006), written by the British author Philip Reeve. Originally known as the Mortal Engines Quartet, it was known in the United States as the Hungry City Chronicles, over the author's objections to this title.

The series is set in a distant future, known as the Traction Era, in which Earth has been reduced to wasteland by a devastating conflict, known as the Sixty Minute War. Nations no longer exist, except in the lands of the Anti-Traction League; whereas Traction Cities – mobile cities mounted on caterpillar tracks – are fiercely independent city-states, which use giant mechanical jaws to dismantle one another for resources. Trade is mostly accomplished by airship, or between mobile cities of roughly equal size (unable to devour each other). Old-Tech (technology from before the Traction Era, some from the 21st century) is the most sought-after commodity.

The Orbital Defence Initiative (abbreviated ODIN) is an orbital satellite weapon; a very powerful remnant of the Sixty Minute War and a major feature of the third and fourth books in the series: Infernal Devices and A Darkling Plain. It was built as part of the arms race between the American Empire and Greater China. It and MEDUSA are the only superweapons known to have survived until the events of the series, although there are several references to other orbital superweapons (Diamond Bat, Jinju 14, and the Nine Sisters, for example). ODIN is more powerful than MEDUSA and is able to hit almost any target on the surface of the earth. ODIN is implied to be an American satellite, as the code for controlling the satellite comes off an American submarine. The other orbital weapons are hinted to have broken up over time and fallen from the sky.