"The Blood-Dimmed Tide" by Howard Weinstein:
This story takes place in 2291, during one of my favorite periods to explore in Trek novels, the time between TFF and TUC. This one is closer to TUC in time frame. Captain Kirk and the Enterprise-A arrive at Mestiko and along with Raya investigate an attack on the scientific base on the moon. They learn a subspace weapon was being developed there and was stolen by another faction from Mestiko. Like the group in Christopher's story, they want Mestiko to be independent and not reliant on help from others like the Federation. However, unlike that group these are not religious zealots. They're fine with technology and advancement. Unlike the earlier group they want to turn Mestiko into a galactic power.
Meanwhile, Captain Spock and now retired Admiral Morrow are secretly meeting with a Klingon General who represents a group that wants more peaceful relations with the Federation because they feel that is better for the Empire in the long term (Gorkon is never mentioned by name, but I think the inference that this is a faction supported by Gorkon is pretty clear). There are more warlike Klingons, including Chancellor Kresh, who believe in a more warlike stance. There is also what I would call a 3rd group of Klingons, represented here by Kang, who are warlike but see the value of honor and have the ability to take the 'long' view. A number of novels depicting Klingons during this period seem to show a transition of the Klingons we know from the original series and the more 'honorable' Klingons of the 24th century. This novel certainly depcts that. Kang is one of those Klingons I know I look at from the original series that even then seemed to have a hint of something a kin to honor--he wasn't just a killing machine.
Anyway, this faction from Mestiko has taken their weapon to a new Klingon dreadnought type battle cruiser and managed to steal this ship to use with their new technology. Kirk and Kang must team up to stop them.
This is pre-TUC and Kirk is still very anti-Klingon at this point. He is disgusted that he has to work with the same people who murdered his son (even if these weren't the ones that actually committed the murder). He is bitter. But he is still a Starfleet captain and knows his duty and follows through as we would expect. It also features a return of Captain Klaa from TFF who wants to use the weapon to usher his own new age of the Empire (so yet a 4th faction I guess). However he is disgraced in the story and Spock forces him into a mind meld to determine where the Mestikan group was going to. This was one of the only elements of the story I did not care for. I think Weinstein uses this to foreshadow the forced mind meld of Valeris in TUC....however, it has generally been pretty clear Vulcans view this as a form of mind-rape. I have a hard time seeing Spock carry this out on Klaa with virtually no hesitation. Ultimately what happens to Klaa is unresolved in the story. He is a prisoner on Kang's ship and that is the last we hear of him (the actor does make an appearance as an interpreter in TUC and it was never specified if it was the same character or not--maybe he was reduced to interpreter in disgrace, though more likely he would be executed).
Overall I enjoyed the story. Despite the Mestikan faction being the aggressors here, this was a story that felt less like a Mestikan story than the others. Perhaps because it's the only story thus far to almost completely take place away from Mestiko, save for the start. At times the Klingon storyline dominates. But it was an enjoyable story nonetheless. In a way it was like a field trip story--a chance to get away from Mestiko for a while.
I also liked some of the interaction between Morrow and Spock. You know, I of course knew Morrow was in TSFS, but i wasn't really thinking about Morrow's role in trying to order Kirk against going back to Genesis to save Spock. That is until Morrow noted the irony at one point. Spock at one point saves Morrow's life and Morrow expresses his regret that he tried to prevent Kirk from going back for Spock. If Kirk hadn't disobeyed, Spock wouldn't have been there to save Morrow. Spock of course tells Morrow his regret is unnecessary. His actions were logical based on the information he had at the time. However, Spock has grown as a character, particularly since two major events in his life, his encounter with V'Ger that Christopher also touches on at times which made Spock realize there is more to life than simple logic. And his resurrection. And he says to Morrow that sometimes, as humans like to say, things do work out for the best. In a way it's a redeeming moment for Morrow. He admits to Spock that had he known then what he does now he would have let Kirk take the Enterprise back to Genesis with his blessings. It was a nice moment for Morrow, a character that sometimes I know I don't care for because of the way he reacted to Kirk's request (even if it was understandable). Saavik is also on board the ship, substituting for Spock while he is on his secret mission. Sulu is not referenced at all, by this point he was captain of the Excelsior.
Just one story to go, Margaret Wander Bonanno's story, which takes place after Kirk's 'death', a Lost Era story basically (though a very early one).