Souls... is the first in a trilogy. It fits into the post-apocalyptic genre being set in Australia nearly 1,700 years after a cataclysmic war brought upon a nuclear winter. The world has recovered from the Great Winter but society is at a pre-industrial/pre-steam level. This is not your Mad Max Australia where brutality and savagery have replaced civilization.
What astounded me about this book is how many concepts McMullen managed to include. He presents some very interesting ways that the society could compensate for lack of steam power, internal combustion engines, and electricity.
Long distance transportation is through a rail system that uses wind or human power. Think of a train where each passenger pedals and their effort is metered. Pedal hard enough and you can earn credit.
Long distance communication is accomplished using focused light between relay towers. McMullen could have left it at that but the operators of the beamflash network, as it is called, take messages, break them into packets, and calculate check sums for each packet, and relay them to the next tower. The packet is eventually reassembled at the destination. This is an analog version of the packet switching network.
The head librarian of the city-state of Rochester, where much of the action takes place, has designed a computer called the caculor that uses humans as components. These components are slaves captured for their math skills by bounty hunters. They begin to think of themselves in terms of their job within the Great Machine: Multiplier 8, Function 9, Adder 17. The reason Zarvora, the head librarian, gives for designing the computer is that government is too complicated to operate without it. Her unstated reason is to predict the arrival of the next Great Winter and to prepare for it.
I confess, being a librarian myself, I like the roles librarians have in this novel. These are not the librarians you see today. For one thing, their education includes weapons training and it isn't unusual for staff problems to be solved through a duel. You can't get away with that today, as effective as it would be. For another, they have real power in the government. The author convincingly shows the importance of information regardless of the state of civilization. Information is power. McMullen also includes some librarian in-jokes about catalogers that are pretty amusing if you have worked in a library.
And, you have the obligatory political and military strife amongst the various states that make up Australia.
But wait, there is more. Another plot element is a hypnotic force referred to as the Call that sweeps over the land at unpredictable intervals drawing all mammals larger than a cat with it. The source and cause of the Call is a subplot through out the book.
Lastly, there is some remnant of the pre-Great Winter age in orbit around the earth. Could it be the reason that technology hasn't advanced in spite of the high level of knowledge and preservation of ancient books in the libraries?
I've read McMullen's book three or four times now and each time I still enjoy seeing how he creates the society, develops the characters, and convincingly introduces modern technological concepts into a pre-industrial society. It has action, romance, political intrigue, and things that make you say "how did he think of that?"