Line War is an excellent conclusion to the Ian Cormac Polity series that started in Gridlinked, though 2 prequels Prador Moon and Shadow of the Scorpion have been published in the meantime. After this review, I will add an overview of the series which has been one of the best large scale space opera this century.
Line War picks up where Polity Agent ended and is all action from start to finish. There are every kind of battles from hand to hand, infantry/tanks against Jain constructs - this is the civilization destroying kick butt tech that is the main enemy in the series and which first Skellor and now Erebus try to use against the Polity - huge spaceships - we see the moon like Cable Hogue kicking wormship butt big time - these are Erebus main battleships, big and powerful - but there are lots of wormships though , informational battles and quite a few other things that I do not want to spoil.
Mr. Crane new and improved by Dragon and highly enraged by Erebus for the killing of his charges on Cull is on a quest for vengeance that ends quite fittingly though not exactly where you would have expected.
Orlandine the Jain controlling haiman - AI enhanced human - that fled the Polity is also on a quest for vengeance against Erebus and convinces some war drones - Knobbler and Cutter being their leaders - to help her against Erebus
Arach the spider like war drone and Cormac' sidekick is back again for action, but this time the AI Jack Ketch does not have a shipbody yet, so it is on the former renegade and still despiser of humans King of Hearts that Cormac and his party embark in their missions related to the war.
Mika, Cormac's friend and lover is again pulled from studying Jain tech to liaise with Dragon and go on a mission
Jerusalem the huge AI warship that is leading the war effort against Erebus seems to be puzzled by Erebus' seemingly random attacks so enlists Azroc a golem that developed a conscience to help predict them.
And of course Erebus itself, the melded AI that wants to become the god of this part of the galaxy - though humans are still pests to be eradicated with some tailored viruses once Erebus controls the rest of the AI's. Though Erebus has some problems itself too with some rebellious ghosts in the machine inside its melded mind. Erebus reminded me a lot of MorningLightMountain of P. Hamilton's Commonwealth duology and he is the best villain of the Polity sequence by far.
Highly, highly entertaining and an excellent conclusion to the Cormac saga, Line War is the best novel in the series, and everything is wrapped up neatly.
Overview of the series:
The Ian Cormac series itself consists of 5 main novels, the standalone debut Gridlinked, and the 2 duologies that build one upon other, but are essentially 2 huge volumes split in 2 big books each- the Skellor event in The Line of Polity and Brass Man, and the Erebus event in Polity Agent and Line War. All the action happens in about 12 years, 2432-2444 , in the huge AI led civilization called the Polity.
In Gridlinked we are introduced to the veteran Polity Agent Ian Cormac - think James Bond without the girls since he is thoroughly dehumanized by many years of direct AI connection called gridlink and he is actually disconnected from it due to imminent danger of burnout. The main villain is Arian Pelter a separatist leader - people unhappy with the Polity, mostly misfits, power hungry persons, or criminals - who has a personal vendetta against Cormac. We meet Mr. Crane the android killing machine in thrall to Pelter, Dragon the planet like mysterious sentient entity first encountered by Cormac many years ago - one of the cool things about the series is how the mysteries between Dragon and his eventual fate are revealed - and various other personages.
Gridlinked was Mr. Asher's debut and hooked me of his novels. A bit unbalanced as most debuts, it is a very, very good book, 3rd in enjoyment in the series for me after Line War and Brass Man. Then after the absolutely brilliant The Skinner set in the Polity 600 years later and still the top N. Asher novel in my opinion, Mr. Asher returned to Ian Cormac in The Line of Polity. This one is the weakest novel of the series though once Brass Man who is the second part was published I appreciated it more. Still the beating on evil, moron followers of a church on Masada and their oppression of poor human serfs just outside the Polity was boring and conventional, though the main villain evil scientist Skellor, the Jain tech and the planet Masada with its weird native creatures become an important part later in the series.
Brass Man, the best novel in the series before Line War concludes the Skellor subplot and brings back Mr. Crane and Dragon in a big way.
Then the Erebus series consisting of Polity Agent which was good but very incomplete being only half of the duology ending now and Line War introduced renegade AI's, most important the melded super-AI Erebus, a renegade haiman Orlandine and the new Cormac sidekick, the bored spider like war drone Arach. This duology is almost non-stop action with big battles of every kind and should be read as one huge novel to be properly enjoyed.