Honor blade - Diane Duane

The previous volume, Swordhunt, ended with the opening battle of the Second Romulan War. Now the war begins in earnest, and Romulans, Klingons and the United Federation of Planets are drawn into an increasingly chaotic web of alliances and betrayals, victories and losses. Behind many of the machinations is the Romulan renegade Ael, exiled from Romulus, hunted by her own people.
Ael is a woman many in the Romulan Senate have sworn to destroy, but many others have sworn to restore. There is Arrhae, the deep-cover Federation agent turned Romulan Senator: Arrhae owes Ael her life - but Romulus her loyalty. There is also Spock, whose fascination with his Romulan cousins will become a lifelong obsession. And there is always Captain Kirk, whose Starship Enterprise is pulled into the maelstrom of political machinations and galactic battles.
As Ael and other warring powers vie for control of the action and the other players, Kirk and the Enterprise are the wild card that could unbalance any scheme - a position that puts them in danger from all sides as they push for the best solution to the deadliest of games!