The Romulan Way (Star Trek #35)

For eight years, Federation Agent Terise LoBrutto has hidden in the midst of Romulans, a race of warriors, a noble people to whom honor is all, cousin to the Vulcan, ally to the Klingon, and Starfleet’s most feared and cunning adversary.

The presence of a captured Starfleet officer forces her to make a fateful choice, between exposure and escape, between maintaining her cover, and saving the life of Dr. Leonard McCoy.