Star Trek: Titan: Fallen Gods (Star Trek books do love their colons), by Micheal A. Martin, is full of interesting ideas and setup. Unfortunately, for the most part, these elements aren't fully realized and resolved. This book picks some serious topics and elides around them as hard as possible.
The story picks up not long after the previous Titan adventure, as chronicled in Star Trek: The Typhon Pact Book 2: Seize the Fire (see what I mean about colons?), and carries through several threads from the larger TNG/DS9 era expanded universe. The Federation is still trying to deal with the massive devastation and dislocation caused by the Last Borg Invasion. At the same time, it is trying to come to terms with the secession of Andor. The Andorians are desperate, in the face of a reproductive crisis that could well reach extinction levels. And the Typhon Pact, particularly the Tholians, are involved deeply with Andor. It's a solid bit of fractured setting to build a compelling narrative of conflicting aims and ends, and in that Martin does a decent job.
Captain Riker and the USS Titan have discovered a planet orbiting an immensely deadly pulsar. Shockingly, the planet appears to be inhabited, a fact made possible only by a hugely enhanced geomagnetic field to absorb and deflect the pulsar's considerable broad-band radiation output. When it appears the artificial field may have some connection to the terraforming device found, and destroyed, in Seize the Fire, Riker decides it might be worth investigating. That investigation becomes even more imperative when a maintenance AI on the planet forcibly mind-melds with Tuvok and an AI Titan picked up in Synthesis, Sentry SecondGen White-Blue; the two Titan crewmembers had attempted a similar link with the terraforming device, and the maintenance AI recognised elements of its makers' code in their minds. But with the mind-meld risky, and potentially irreversible if left to continue too long, the pulsar getting steadily more violent and the geomagnetic field on the edge of collapse, such an investigation could be dangerous. Add to that a civil war being fought by the descendants of the Ais builders on the planet, between Preservationists/Keepers and Deconstructonists/Trashers, Starfleet Command's orders that all Andorian officers be reassigned to 'less sensitive' positions, and Andor's demands that all reproductive-age Andorians be sent back to Andor and the newly-reconstituted Imperial Guard's willingness to enforce that order, and you have a pretty wild set of circumstances that would allow for an exploration of any number of issues.
Unfortunately, as I said, Fallen Gods does not fully embrace its difficult subject matter. Much time is given to establishing the alien civil war, including several chapters from the viewpoint of the Preservationist leader, but ultimately it's never really an issue for the Starfleet characters in the book. It's a thing that's happening when they reach the planet, something that inconveniences them slightly, but no more than bad weather or predatory wildlife would've. The same is true of the efforts to get the maintenance AI back to the planet and the magnetic field generators repaired. The book spends ages having characters discuss the pros and cons of going, of how to go, of when to go, and then covers them actually going. But then they just drop the maintenance AI off in a convenient console and leave, playing no role in actually resolving any of the issues. The worst-handled storyline, however, certainly belongs to the Andorian Imperial Guard's efforts to 'liberate' reproductive-age Andorians from Titan.
The book skirts around the AIG commander's plan for an unnecessarily long time, since anyone familiar with The Next Generation should quickly figure out what it consists of. Unfortunately, with all that evasion and forced mystery, there's no time left to delve into the ramifications of it, which are absolutely massive. The moral stain on the Andorians who are participating in it, the mental anguish and existential collapse of the Starfleet Andorians subjected to it, neither are given any particular weight. Indeed, the actual issue isn't directly addressed by any characters until literally the last page of the story. One can only hope, rather desperately, that the next book will actually put some work into exploring this issue on a personal and societal level, rather than faffing about with artificial mysteries that dedicated Star Trek fans (and who else would be reading a Star Trek: Titan book?) will see through in a few pages.
Fallen Gods has all the pieces necessary to be a really compelling novel. Frankly, it has all the pieces necessary to be several really compelling novels. But its refusal to actually engage with any of its topics in detail, to build up meaningful drama and suspense, to present serious threats and stakes, hampers it. The book is enjoyable enough while you're reading it, but upon putting it down don't be surprised if your first thought is a rather plaintive, 'Is that it?'