The full plot of the book revolves around the misterious Tomed Incident, often referenced in the Star Trek saga and finally explained.
It is all about a covert sabotage operation to simulate a Romulan attack forcing the Klingon to part with the Federation effectively ending a possible all-out war between the Federation and the Romulan Star Empire.
Unfortunately the whole plot is very weak and, reasoning on it, a lot of plot holes surface.
Worse than this, the book fails in keeping the attention of the reader and you simply have to cope with endless description with no action at all.
Not a bad book, after all, but very far from an optimal and involving action and espionage novel.