That's the really short version of it.
The slightly longer version is Orion's Hounds is about the bond between hunters and their prey.
Star Trek has a long and storied history of the relationship between humans and hunting. For a science fiction series primarily concerned with issues of science and sociology (when not about explosions), it's amazing to realize just how many episodes are devoted to talking about humans and killing animals for food or sport.
Star Trek has the Eska, Hirogen, and (of course) Star Trek IV: The Voyage Home for talking about the evils of hunting. Vulcans are strictly vegetarian and it's implied that most Post-Enterprise humans find the idea of eating organic meat (as opposed to replicated meat) to be disgusting. To say that the series squarely falls on the side that hunting is wrong is a bit of an understatement.
Captain Archer actually says that humans no longer hunt as of the Enterprise era. You know, despite the fact that humanity just emerged from a nuclear war where the majority of mankind had to take their next meal wherever they could get it. As you can probably guess, I'm not terribly fond of this premise. Humans are a part of nature and nature has a clear pecking order. I don't approve of abusing animals but I also don't see anything wrong with eating them.
Call me crazy.
Orion's Hounds is interesting because it simultaneously reinforces Star Trek's usual stance that hunting is evil while also undercutting its traditional environmental justification. Star Trek has a very strong pro-environmental message to it, one I approve of. However, many environmentalists in real-life seem to think that being pro-nature also means being anti-hunting.
One thing that a lot of these anti-hunting activists are uncomfortable with is that, quite bluntly, hunters love the environment. They also love animals with a passion you won't normally find in many people.
I grew up in Northern Kentucky next to rural West Virginia and I can tell you that if you want someone to tell you about deer or the forest then you should probably go into a dedicated hunter. They hate when forests are torn down and they despise when animals are poisoned by local industry. In a very real way, their chosen lifestyle puts them in communion with nature in a way that makes them very angry whenever the environment is despoiled.
Orion's Hounds follows the crew of the U.S.S Titan as it comes across the troublesome situation of a race of interstellar nomads called the Pa'haquel hunting the sentient "Star Jellies" from the Star Trek Episode "Encounter at Farpoint Station." Under most circumstances, this would be a strictly black and white situation. As a general rule, if you're hunting people for sport you need to put down like the monstrous animal you are.
In fact, one of the biggest weaknesses of the book is that crew reacts like this is a morally ambiguous situation. It's not even a case of the Prime Directive being at play because both the Pa'haquel and the Star Jellies have warp capabilities. No, there's just an actual argument over whether or not the crew of the U.S.S Titan has the authority to intervene in a case of one culture hunting another for sport. This almost made me want to hurl the book against the wall but I persevered and they eventually gave a reason why there should be any debate on the subject.
Still, the work goes into a much more interesting place than that. Rather than just stock villains, the Pa'haquel have a culture which partially justifies the heinous actions they do. They're also detailed enough that they're actually interesting to read about in their own right.
One of the fatal flaws in exploratory science fiction is the cultures encountered often prove to be less than page turners. In this case, I actually wanted to know more about the Pa'haquel at the end of the day than regretting I'd devoted hundreds of pages to learning about them. The Star Jellies were less interesting to me but still had a number of interesting scenes devoted to their life-cycle and mating habits.
William Riker manages to do much better as a Captain here than in previous books. Where he was earlier largely ineffectual in resolving the situation, here he manages to accomplish a great deal more based on his skill as a captain. Likewise, Deanna Troi gets a larger role than she did in the show. Her psychic abilities play more of a role than as set-dressing and her diplomatic skills actually get some play.
Sadly, my favorite of the Titan characters in Christine Vale suffers a bit. She is naturally contrary to every position that Riker holds, even when they change. Basically, she just exists to give the opposite argument of whatever is proposed by our captain. At one point she also goes into a bizarre rant against gun ownership that makes no sense in the 24th century and comes out of nowhere.
Overall, I liked Orion's Hounds. While I'm a bit disappointed it had nothing to do with the Orion race of "Orion Slave Girl" fame, I felt it really brought home the Star Trek handles social issues' feel of things. While disappointed that the characters had a bizarre hesitation over whether to intervene in the persecution of the Star Jellies or not and Christine Vale's characterization, this is what I like my Star Trek to be about.