The Fever Crumb Series is the prequel series to the Mortal Engines Quartet and is written by Philip Reeve. The main hero of the series is Fever Crumb. The first book, Fever Crumb, was released in 2009, the second book, A Web of Air, was released in April 2010 and the third book, Scrivener's Moon, was released in April 2011.
The Fever Crumb series is the return to the World of Mortal Engines. After Philip Reeve finished writing A Darkling Plain, he said that he was fresh out of ideas for the World of Mortal Engines. However, after he had completed writing Here Lies Arthur and the Larklight Trilogy, he said that he could refresh the world by going back a thousand years to the dawn of the Traction Era. Philip Reeve has also stated that the series will be more scientifically accurate than the original quartet.
The series is set a thousand years before the events of Mortal Engines, and London has not yet become the first Traction City. In the North the Nomad Wars are being fought, threatening to come south and invade. The Scriven had ruled London for two-hundred years. Archaeology is the main trade and wheeled Land-ships trundle across Europe. As airships have not yet become a conventional way of travel, it's harder for people to travel over mountains or oceans. The story tells of the dawn of the traction era and the birth of Municipal Darwinism.
As the tale is set mostly on the ground, there are a lot more types of species than seen later on. Hairyphants roam the lands to the north in the Arctic. Semi-intelligant Mutant seagulls live over Mayda. Apart from animals, there are new sub-species of humans, such as the Scriven and the Nightwights.
The Second book in the series called A Web of Air was released in April 2010. Philip Reeve has stated that there will be at least four books, although the future is uncertain. Reeve has mentioned several possibilities for the series. He has said that if Fever Crumb survives the events of A Web of Air then he will send her to places that he never had time to explore them in the original quartet. He has also mentioned the possiblilty that Fever Crumb to live far longer than normal humans, due to her mother being a Scriven and the stalker cells in her blood. He has even suggested that she could live to the time of Mortal Engines; however, Reeve does not plan any more than a few chapters ahead, meaning she could die at any time, leaving the series to be continued by a new character.
There are also several things mentioned on the official Philip Reeve site that may be seen in future books.