Tell No Lies by Allison Brennan

Something mysterious is killing the wildlife in the mountains just south of Tucson. When a college intern turned activist sets out to collect her own evidence, she, too, ends up dead. Local law enforcement is slow to get involved. That’s when the mobile FBI unit goes undercover to infiltrate the town and its copper refinery in search of possible leads.

Quinn and Costa find themselves scouring the desolate landscape, which keeps revealing clues to something much darker—greed, child trafficking and more death. As the body count adds up, it’s clear they have stumbled onto much more than they bargained for. Now they must figure out who is at the heart of this mayhem and stop them before more innocent lives are lost.