The Rings of Tautee (Star Trek #78)

When a solar system begins to disintegrate, Captain Kirk suspects that rumors of a new Klingon superweapon are true. The Tautee system houses a flourishing pre-Warp civilization not quite ready to join the Federation, so the Prime Directive limits Kirk’s ability to undo the disaster, and his humanitarian rescue operations provoke a hostile response from four Klingon warships.