Be Still My Vampire Heart by Kerrelyn Sparks

Angus MacKay, a Highland warrior turned vampire, has been undead for nearly five centuries. His existence is disrupted when he encounters Emma Wallace, a CIA agent from the elite Stake-Out team. Emma is determined to rid the world of vampires, driven by the tragic loss of her parents to these creatures. However, as she crosses paths with Angus, she discovers that not all vampires are her enemies. Amidst their conflicting missions, a passionate and dangerous attraction ignites between them. Will love triumph over duty, or will their differences tear them apart?