Add to this intriguing setup a culture which places great emphasis on personal combat -- duels. And one more odd feature -- a mysterious Call, to which every animal larger than a cat, including humans, is subject. When the Call happens, once every several days, all these higher animals are compelled to head in one direction, until the Call ceases. Humans have devised tethers, to keep them in place until the Call frees them, and "Mercy Walls", which they run into and push against until set free of the compulsion. If human are careless enough to forget their tether, or to be outside or away from a Mercy Wall, they will head in the direction of the Call, even if it takes them into a river, or over a cliff, or into somebody else's territory. The unlucky die, the luckier ones may simply wake up from the Call to be taken into slavery. The really lucky ones just have a long walk back to their home.

Into this mix Sean McMullen throws Lemorel, a young provincial woman and a talented mathematician, whose ambition has led her into several duels. She ends up at Libris, with many other talented mathematicians, supporting the Calculor. There is also Zarvora, the odd genius who has invented the Calculor, and who has some mysterious use for it besides simply improving communications and tax collection. And Lemorel's talented but untrustworthy sometime lover, John Glasken. And Dorian, the mute linguist who befriends Lemorel. And Ilyire, a strange man from beyond the deserts at the edge of civilization, with an even stranger talent. And more, as the book continues.

The ideas behind this book are truly fascinating and original. I was kept reading simply by curiosity about things like the Call, and the real reason for the Calculor, and the cause of Greatwinter, and so on. And it must be said that McMullen mostly delivers in this area. The rationale for his future -- the source of the Call, the reason electronics cannot be used, the origin of Greatwinter -- all these are given explanations that work well within the context of the book (although some of the explanations are a bit far-fetched scientifically). But I still have considerable reservations.

My problems with the book were in two main areas: characters and plot. The characters are a strange set of, basically, obsessed madmen and madwomen. When the plot requires it, they are happy to fall instantly in love with a stranger, and commit murder, start wars, whatever, to resolve their relationship problems. Moreover they are all essentially immoral. For example, Zarvora, perhaps the closest thing to an overall heroine in the book, kidnaps and imprisons people for years to make the Calculor work. Lemorel has killed something like a dozen people before the book starts. Similar things can be said of many other characters. Indeed, heroes become villains and vice-versa with some regularity. This can be made to work, but not when it is done arbitrarily, as seemed the case here.

The plot is discursive and disjointed. Long stretches dragged alarmingly towards the middle of the book. At times, the author resorts to summary, and authorial voice explanations of tricky bits, in order to advance us to where we need to be. I have a notion that this is partly due to the original source of the book. It seems to be cobbled together from McMullen's first two novels, Voices in the Light and Mirrorsun Rising, which were apparently only published in his native Australia. (Some of his short stories were also incorporated in this novel, I assume, based on titles like "The Glasken Chronicles.") The joins show.

On balance, I do recommend reading Souls in the Great Machine. It has definite faults, but also definite good points. The ending is rousing and fairly satisfying. Even though the characters are not very believable, they are interesting. And the book is marked by a definite exuberance that makes it a fun read.