The inevitable and inescapable state of humankind is war. Such, at least, seems to be the conclusion we must draw from the third part in Paul McAuley's ongoing series.

All three of these novels have been, in their way, war stories. But The Quiet War, written at a time of the protests against the Iraq war, focussed on peace protests and efforts to prevent war in its portrayal of an escalating conflict across the solar system. The second volume, Gardens of the Sun, coincided with the confusion and disarray that followed the Iraq War, and reflected that in a story about efforts to restore some sort of normality in the aftermath of war. Both novels, in other words, questioned war. There is a sense, in this new volume, that the questions have been allowed to lapse.

The two earlier volumes moved restlessly among numerous viewpoint characters, evoking a multi-layered perspective, allowing us to piece together very different responses to events. This new volume tells the story of only three characters, arranged quite formally so that we always move from one to the next according to a strict pattern. And each of the three is directly involved in conflict. There is some ambiguity about which side in the conflict might be right (although, because we never see anything from the viewpoint of the Ghosts, and because they are presented as the aggressors, we seem to be obliged to consider them in the wrong), but the idea of conflict itself is never questioned here as it has been before.

We are some thousands of years after the conclusion of Gardens of the Sun. Those humans who fled conflict in the solar system in that novel have long since reached Fomalhaut. The Quicks arrived first, establishing a civilisation that thrived for a while then began to decline. In their wake came the True, who found a system ripe for taking over, and in the process they enslaved the Quick. More recently, the posthuman Ghosts have started turning up, and immediately engaged the True in battle. Humanity's most successful exports to the stars would appear to be slavery and warfare.

This, then, is the situation at the start of this new novel. It is so far removed from its two predecessors that it can easily be read as a standalone novel, but it does gain extra resonance from its relationship to the other two books. Not least because one of the central characters in this new novel, referred to throughout as "the Child," turns out to be one of the prime movers in the earlier books. She is dead, of course, after so long a time how could she be anything else, but in this future death is not necessarily an absolute. So the Child is being raised in a small, remote community in the Amazon. All seems peaceful, but in fact there is a perpetual guerrilla war being waged in the surrounding jungles. But there are signs that things are not all as they might appear, not least the Jaguar-headed boy who might be an avatar of local myth or who might be an agent of the guerrilla forces, but who is in either case a symbol of freedom and escape to the girl. As we soon realise, the Child is in a simulation, being raised and trained by her distant descendants in a ship that is finally, and belatedly, approaching Fomalhaut. But the ship has been damaged and delayed on its journey, both the Quick and the True have passed it long since, and the computer system that sustains the simulation has been damaged also, which is why glitches and oddities intrude upon the Amazon community she inhabits.

The Child is important to the crew of the ship, for reasons that are never fully articulated. She seems to occupy a sort of mother goddess role and must be reborn exactly as she was; therefore, the crew are intent on insuring she undergoes an upbringing as close as possible to that experienced by her real-life original before they reach their destination. Yet others are aware of the approaching ship and seem to hold its revered passenger in similar regard. As we discover, it is one of the things that has triggered the latest round of warfare in the Fomalhaut system.

The Child's story is told in the third person by an unnamed member of the crew overseeing her education. Ori's tale is told in omniscient third person. Ori is one of the Quick who starts the novel as the remote pilot of a small ship performing heavy duty around the Whale, a massive space station hanging in orbit over the gas giant Cthunga. Some time in the past a Mind crashed into the gas giant, and the Whale is now the centre of confused efforts to contact it, because the True have a mystical belief that the Mind might have achieved some sort of transcendence and prove their salvation against the Ghosts. During routine work outside the Whale, Ori witnesses a blue spark that might be the spirit of the AI. This is enough to bring her to the attention of her True masters, and, never quite in control of her own destiny, she is moved throughout the rest of the novel in such a way that she always finds herself at the centre of the action as the Ghosts launch their latest attack.

The third strand is told in the first person by a Librarian, which in this world makes him an action hero. He failed once, on a mission in which two of his fellows were killed, and now lives out his disgrace killing demons. Arthur C. Clarke once said that any sufficiently advanced technology is indistinguishable from magic, and Clarke's heirs have taken that message to heart. It is now rare indeed to find a novel set in the far future that does not use the affect and often the language of high fantasy, and McAuley's work is no exception. The Librarian, and his Quick assistant, Horse, are actually engaged in disabling advanced but decaying Quick technology that threatens the digital world they inhabit, but the rogue technology does manifest itself as fire-breathing demons. And their latest mission which, as is the way of these things, brings us back to the failed mission that brought about the Librarian's disgrace, also suggests a back door into the Library itself, the accumulation of knowledge upon which their whole world is built.

It is, as this synopsis might suggest, a plot-heavy novel, full of dramas and spectacle. The Librarian engages in an escalating succession of combats while on a headlong chase that takes in a whistlestop tour of stations and worldlets and digital scenarios. Ori is forever being pushed backwards and forwards through full scale space battles, major disasters, and small scale abuses. Only the Child seems to have time to look around and take in the scenery, which in this case is an evocation of an Earthbound landscape; but conflict is the constant background to this sylvan scene, and she is always struggling to make sense of various mysteries, betrayals, confrontations and flights. We are, in other words, never at rest. The solidity that made The Quiet War in particular such an effective evocation of what it might actually be like to live on other worlds is here replaced with breathlessness and hurried glimpses. There is little real sense of how or where most people live around Fomalhaut, but rather vague suggestions that we do not have time to take in before we are rushed off to the next conflict. It is as if, the further we are in space and time from the known realms of our solar system, the less there is to say about setting and circumstance.

Which is not to say that this is a bad novel. Far from it. McAuley is one of the most accomplished writers currently working in what we call hard SF. His prose is evocative, his characterisation is convincing, and his plotting never less than gripping. He draws us in to the story, and holds us there, feverishly turning the pages to keep up with rapidly evolving events. It is just that The Quiet War set a very high standard, and In the Mouth of the Whale struggles to match up to it. It is noticeable, for example, that where The Quiet War painted nobody as an out and out villain, everyone was working towards what they sincerely believed was the good; in In the Mouth of the Whale there is a much simpler division between those we want to cheer and those we are meant to boo. A layer of political and emotional complexity is missing from the new novel. Maybe it is better to read it as a standalone work, completely detached from what went before. In that respect, it is an exciting and enjoyable tale, full of blood and thunder and spectacular set pieces. But it feels that there is too much of the drama and the conflict, and not quite enough of the subtlety, of the convincing portrayal of our future in space that was the hallmark of its predecessor.

Paul Kincaid is a recipient of both the BSFA Non-Fiction Award and the Thomas D. Clareson Award. His most recent book is What It Is We Do When We Read Science Fiction.