It is 2129. Humanity failed to do anything about climate change, and the rising temperatures led to a slow flooding of all coastal cities and a massive flood of refugees inland. Simultaneously, desertification of the temperate regions of the land lead to plummeting production of food, and a starvation risk.
There's therefore only one solution. To the sea!
Underwater colonies, set up on the continental shelves allow farming of carefully selected plants that grow in a water environment, while also getting people off the land. It's relatively early days (with only 10 million people living their lives underwater), but as a project it's going reasonably well.
Except in the life of Truman McClusky.
He lives in Trieste City, just off the coast of, and about 30 metres below, Florida. The city is under US control, and has only been more so ever since his father (the former mayor)'s failed rebellion, which resulted in nothing but his dad's death, his sister's departure for another city off the coast of Australia, and McClusky's derision of the idea of independence for the underwater cities.
Since Trieste is well established, it even manages to have its own intelligence service (somewhat unimaginatively named "Trieste City Intelligence"), and until recently, this was where McClusky worked. Unfortunately, he found himself betrayed by a close friend, Johnny Chang, and captured by a Chinese underwater city, and then tortured for months. After being released under a prisoner exchange, he wanted nothing more than to keep his head down and grow some kelp.
It's a shame then that his old friend/traitor has popped back into his city, and stolen an exciting new technology that might finally lead Trieste to an independent wonderland. Now McClusky has got to go back to work with Shanks, his old boss, and Katherine Wells, the aquanautics scientist who designed the sea-car he's going to be chasing down Shanks in.
This is very much in thriller territory, slightly out of my usual, but not bad for all that. It feels similar to something Lee Child might write, but also has hints of Andy Weir's Artemis. The underwater cities face a similar but inverted pressure problem to Artemis' moon bases, such that if you leave them at the wrong time, you might implode rather than explode.
That book's combination of science and fiction is well presented here, with a nice level of technical detail put into the difficulties of surviving at pressure. Everybody lives at four atmospheres, and the intricacies of standardising working environments and dealing with a living space that will happily kill you is nicely explored. The same is true of the various mysterious technologies that are driving the still persisting East-West conflict. I'll admit to a complete lack of knowledge about the troubles divers face, but it seems convincing.
While McClusky falls rather strongly into the "action hero" mould, there's some tweaks to his personality that allow a more thoughtful approach to some of the problems he faces. Good to see. At the same time however, if you're here for thrills, the book will deliver. Lots of underwater punching, and no lack of torpedoes. Some excellent extrapolations to the possibility of undersea international war and how that might look at the pointy end of a harpoon gun. Slightly awkward romance, that feels a bit bolted on, but that's the Bond girl problem for you.
Overall, a decent, fairly fast-paced read, that appears to be heading into series territory.