Survival: Species Imperative (Book 1) by Julie E. Czemeda
This book is part of a series, “Species Imperative.” However, it can be read as a stand-alone novel.
The book proceeds sort of like a chase movie. After being introduced to the characters and setting, we learn of a threat from bad guys. Then it's running here and there, while finding out more about the players.
The central character is a woman biologist studying salmon on the west coast of Canada. The salmon are just beginning to run when her work is interrupted by the arrival of an alien archeologist who has become interested in her work. (I, for one, never figured out what he thought her salmon studies would contribute to his project.)
The alien is studying the disappearance of all life from an area of the [galaxy? universe?] several thousand years previously. He suspects it may be connected to a series of incidents where more localized tragedies occurred on a series of planets in recent years. He also believes there are forces that don't like his studies and would like to stop it.
Events start building up at the research station, suggesting the woman scientist is now in serious danger as a result of her association with the alien. The woman and alien are evacuated to the alien's secretive home world. On the trip there and on the planet itself we are introduced to various aspects of this [non-humanoid] alien species' lives and culture.
And then, as often happens with chase and thriller stories, we have a quick sprint through the final showdown and wrap-up at the end.
It also has a romantic angle that strikes me as being decidedly more to women's inclinations. (This is consistent with the author and protagonist both being women, although the protagonist is a scientist who does not fit feminine stereotypes). But there's something in the flavor of the sudden romantic attraction and expectation of substance to it that is at least more common with women and/or youth.
The point of a chase / thriller story is not to maintain complete internal consistency or avoid circular reasoning (or if that is the point, most such stories miss the point). This is definitely not a story to sit back afterwards and admire the logical perfection. But as long as you're not looking for that, you may very well find it a decent SF chase.
If you are interested in the science angle, there were some murky areas. For instance, they have some instantaneous interstellar travel that sounds kind of like going through a wormhole (except the same fixed-location entrance seems to take you to whatever exit you want). When a character uses one of these to go to another star system, there's a comment that the light of this other star will take millions of years to reach Earth. Perhaps, I was just assuming (because I was unaware of any statement to the contrary) that this other star was in our galaxy. But a distance of millions of light-years would certainly put it far outside the Milky Way.
Then we are told this star system has been cleared of all but one planet in order to eliminate hiding places for enemies. I couldn't quite figure out the point of this enormous task, as it would not prevent enemy spaceships from being in the system. If there were detectors that could spot enemy ships, they could be put on the other planets; if they didn't have detectors, the planets would not interfere with the use of detectors...
On the planet there's a constant monsoon-like rain. It says this is being intentionally done to empty an ocean on one part of the planet and relocate the water. Is this a likely way - for a species that has removed planets from its solar system - to relocate an ocean's water? (Especially if you’re a species that does not drink water, but excretes water – so it’s like creating a constant torrent of urine.) To nitpick further, we can’t be talking about an “ocean” like those on Earth where the Atlantic, Pacific, Indian and Artic oceans are just regions of a contiguous body of water. Rather, we’d have to be talking about an inland sea.
Interspersed between chapters about the main plot, are little chapters describing what happens on various planets when a "green rain" falls and causes all life-forms to dissolve. The liquefied remains collect into areas of liquid and then a mouth comes to drink it. Initially, there's no explanation what the mouth is part of, where it came from, how it got there, or how the "green rain" was dispensed. Eventually, we are lead to draw a conclusion about what the mouth is associated with. We're never really told how it got there, how such large amounts of green rain were produced, etc. Nor was I left with a satisfying feeling of why...