Demands of Honor
You may be looking for Demand of Honor, a Star Trek: The Role-Playing Game module from FASA.
Continuing the all-new trilogy!

Demands of Honor is a Pocket TOS novel – the second novel in the Errand of Fury series – written by Kevin Ryan. Published by Pocket Books, it was first released in .

Summary 
From the book jacket
The United Federation of Planets and the Klingon Empire stand on the brink of war. Captain James T. Kirk and the Starship  are sent back to System 7348 – site of a previous skirmish with the Klingons – for a confrontation with the IKS D'k Tahg under the command of Captain Koloth.

Even as the two great ships face each other, trouble is brewing among their crews. On the Enterprise, Lieutenant Leslie Parrish is pregnant with a half-Klingon child and must face a critical decision about her future, while Section Chief Michael Fuller still carries the wounds of the twenty-five-year-old Battle of Donatu V, of which he was one of the few survivors – not to mention his grief over the death of his son, recently killed in battle against the Klingons.On the D'k Tahg, First Officer Karel finds himself trapped between the scheming, dishonorable Councillor Duras and his commanding officer, Koloth. While the stakes only seem to be the possession of a single star system, the ramifications may spread throughout the Klingon Empire, as they find themselves between conquest and honor!''

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Novels