The Romulan Way
Second in the Rihannsu Sequence.
"They are a race of warriors, a noble people to whom honor is all. They are cousin to the Vulcan, ally to the Klingon, and Starfleet's most feared and cunning adversary. They are the Romulans, and for eight years, Federation Agent Terise LoBrutto has hidden in their midst. Now the presence of a captured Starfleet officer forces her to make a fateful choice between exposure and the chance to escape: maintain her cover -- or save the life of Dr. Leonard McCoy? Here, in a startlingly different adventure, is the truth behind one of the most fascinating alien races ever created in "Star Trek" -- the Romulans."