Sean McMullen's inventive and complex novel Souls in the Great Machine takes place in Australia, 2000 years in the future, following Greatwinter, a nuclear winter which nearly devastated the Earth.

In McMullen's Australia, electricity doesn't exist due to battle satellites which attack sources of electromagnetic power, and steam power is proscribed by religious doctrine. Rail travel is by wind power or pedal power. A phenomenon called the Call sweeps periodically across the land, drawing mammals over a certain size (including humans) in a mindless walk south unless they are restrained by tethers, anchors or walls. And across the sun, a steadily growing band, called Mirrorsun, threatens to bring back Greatwinter.

Government is based on libraries -- and librarians rule. (Well, I've always said that, but did anyone believe me?) Promotion to different ranks of librarian is based on examinations, including tests of marksmanship -- because disputes are settled by duels. The highest ranking librarian of all, the Highliber, is in charge of Libris, the mayoral library of Rochester, and this particular Highliber, Zarvora Cybeline, is one of the youngest ever -- and possibly, the most brilliant. She has developed a secret machine, the Calculor -- a computer which uses humans as its components -- a creation with mind-boggling ramifications.

To Libris comes Lemorel Midorellen, a young woman with the potential to rival Zarvora. At first, she is an ally as the Highliber begins to fine tune her domain, but as the years pass, Lemorel's instability increases, and soon the two are bitter rivals engaged in a war for control of the entire continent -- a war which disrupts Zarvora's work toward destroying the Mirrorsun and preventing another Greatwinter.

The sheer scope and complexity of the novel is mind-boggling, yet the reader is able to grasp and follow the plot without too much difficulty, once the basic concept of the society is established. McMullen raises a number of issues about technology, society, genetic engineering and morality, weaving them swiftly and skillfully into the story. McMullen never takes himself entirely too seriously; whimsy and humor have their place, as when the captains of the Great Western Railway express their nearly fanatical adoration of the 19th-century railway engineer Isambard Brunel, saying that when they experience problems, they ask themselves what Brunel would have done, or the silver hens that peck out the Calculor codes on paper tape. As a librarian, I found it amusing to see that some things, especially in cataloging departments, never change.

The characters are well-rounded, complex and fascinating, and while at first it seems as if the reader would need a scorecard to keep them straight, each of the primary and secondary characters have distinct and unique personalities, and they are vividly realized.

At a few points in the novel, McMullen's leaps over great gaps of time lead to some confusion, and it seems that production is rather high, especially of books and paper, for a relatively low-tech society, but these flaws are far outweighed by the sweep of the story. The best news is that more Greatwinter novels are on the way.