Night of Mercy by Jo Grafford

Prim Midraven has been following her mother’s dating advice for years. You should be able to trust a professional matchmaker, right? Which doesn’t explain why Prim is still single and lonely.
When her best friend, Deputy Shep Whitaker, organizes a volunteer K-9 search and rescue team at the poverty-stricken reservation where she works, she ignores her mother’s advice (for once) and signs up as his first volunteer. His only volunteer, as it turns out, which is why she can’t simply quit on him after her better judgment kicks in. Sure, he checks every box on the list of things she’s supposed to be avoiding in a relationship, but no biggie. They’re both adults, and they’re both professionals. What’s the worst that can happen while working with him on a strictly volunteer basis for a few weeks?
Apparently, a few things she never considered — like getting caught in the crosshairs of a dangerous enemy together. Oh, and accidentally falling for her hunky friend in uniform. It’s way past the point where her mother would advise her to cut her losses and run. So why is her heart telling her to stick around and find out where their spark of attraction might lead?