Rules of Engagement (Star Trek, Book 48)

A sudden revolution on the planet Dekkanar brings Captain Kirk and the U.S.S. Enterprise? running to evacate Federation personnel trapped there. But their orders from Starfleet are quite clear; the U.S.S. Enterprise is to assist in the evacuation, no more. No weapons are to be displayed, no shields raised, no shots fired.

Meanwhile, halfway across the galaxy, an experimental Klingon warship sets forth on a mission of its own, a warship with hidden -- and heretofore undreamed of -- capabilities, commanded by a warrior who will stop at nothing to bring glory to his Empire -- and restore his own lost honor.

the Klingon ship's destination? The planet Dekkanar...