Just Enough Light by AJ Quinn

Kellen Ryan has taken the survival skills she learned on the streets and used them to create an elite search-and-rescue operation, as well as the first home she’s known in forever—a sanctuary in Haven, Colorado, high in the Rockies.
A small mountain town was the last place Harvard-educated Dr. Dana Kingston expected to find herself. Still, when she’s offered an opportunity to partner with Kellen’s operation and develop a medical triage center, Dana follows her heart. Dana falls hard and fast for the enigmatic Kellen. But she quickly realizes Kellen’s heart is as carefully guarded as her past, and breaking through will take time. Except time is the one thing they may not have, because a deadly threat has returned, and this time he plans to finish what he started