Promise. The Naravan Chronicles, #1

Kira Farseaker led a sheltered, privileged life-until the discovery of a secret that plunged her into an underworld of danger. Now she fights to save an alien species, the Shifters, from government-sanctioned extermination. When she learns some of the Shifters are evolving, she vows to give them sanctuary on a secret planet, a Farseaker legacy. But getting them off-planet and safely to the promised haven will be the most dangerous mission she's ever attempted.
A challenge made more deadly by her attraction to the dark, hungry eyes of a suspected spy. Officer David Cario's assignment to a Shifter extermination squadron might be just the break he needs to uncover the secrets behind his sister's execution. But earning the trust of his commander's ex-wife, the suspected terrorist Kira Farseaker, proves more complicated than he planned. Crossing into Kira's world will lead him to truths he isn't prepared to discover, and the desire between them destroys everything David once believed.
Tangled in a web of treachery, Kira and David struggle between duty and a growing passion that could destroy everything they've worked for.or save both their lives. This book was previously published as The Promise of Kierna'Rhoan