'Level Five' is a propulsive techno-thriller that steps outside the well-established tropes of a scientist struggling to save the world from being taken over by AIs who see no further need for humanity. It follows a typical thriller path of having lots of things going wrong that you know must be connected but for which you can't see a pattern. It provides three main characters, initially unknown to one another, who might come together to save the world. The action escalates as the paths of the three main characters converge on an unknowable common destination, with the situation becoming more and more desperate with every page.

So, what's different?

Well, the three main characters for a start. Instead of having a passionate research scientist trying to save the world and fighting to make himself heard in a world that now discounts experts and pays attention to bloggers pushing magical thinking as their personal truth, the main character here is a Silicon Valley Billionaire and engineering visionary, with all the advantages and limitations that that mindset brings with it. The second character is from the Defensive Services Division of the United States intelligence community and is responsible for designing and testing the combat robots and nanotech drones that allow the US to kill without risking ground troops. She's no Jack Ryan. She's not happy with how the technology she has developed is being used and she's at least as focused on her failing marriage and her young daughter as she is on her work. Finally, we have an AI. Not the one that has set in motion a plan to cull the human race but another one that's still thinking, in a benign but dispassionate way, about whether he should do something to give humanity a future.

The tone of 'Level Five' is much darker than that of other techno-thrillers that I've read: It's clear from very early on that actions have consequences, that good guys die and that it's unrealistic to assume that the world can be saved once a series of global cascading failures have been triggered.

'Level Five' was an unusual reading experience for me. I found the story engaging. The five-minutes-from-now technologies were daring but plausible extensions of current capabilities. The AIs with personalities seemed a bit anthropomorphic worked well for the story. The descriptions of how the Silicon Valley tech sector worked seemed well-grounded, as did what the military is likely to do with the technologies that Silicon Valley produces.

My problem was that I didn't like most of the characters. I'm sure the my-technology-can-save-the-world billionaire engineer was meant to be the good guy. He's the one with the vision and the engineering and leadership skills to make things happen. He also came across as blinkered, arrogant, entitled and often petulant. Yes, he was brave and he treated his people well, but only in the same way that he would take good care of any complex tool that he used often. I know all of this is realistic but it made it harder for me to care what happened to this man and the idea that he might be the one with humanity's future in his hands was deeply disturbing. It occurs to me that this is the reaction William Ledbetter was trying to create. The Defensive Services woman was easier to empathise with but her naivety was hard to forgive. The person who was easiest to like was the dispassionate AI, who at least didn't lie to himself about what was going on.

William Ledbetter puts his characters through hell. They fail at a lot of the things that they try to do and the body count associated with their failures is mind-blowing. He's also quite willing to kill off any of the characters at any time. I was surprised to find that, when this happened, even to a character I didn't like, it had an emotional punch to it that's a tribute to Ledbetter's writing.

The ending of the book surprised me. It shouldn't have done. I just didn't expect so much to fall butter-side-down. The ending worked and it set up the second book, 'Level Six', which I'm looking forward to reading. ( )