The Green Children - Sycamore Moon, #3

After missing for three days, a young girl is found wandering the Arizona forest. She's despondent, with no memory of her ordeal beyond eerie delusions. When a second girl disappears, a pattern emerges that sets two police departments racing against the clock to save her. Only two men dare take on the mysterious Sycamore wilderness: Maxim Dwyer is a small-town detective with attachment issues who faces off against a rival from the county police.
Diego de la Torre, a biker troublemaker with an anti-authority complex, walks a fine line between responsible citizen and vigilante outlaw. Together, the unlikely pair isn't always on the same side of the law, but they are the girl's best hope. Unfortunately, things in Sycamore are rarely what they seem. Maxim and Diego have more problems than they know, and if those don't catch up with them, whatever lurks in the forest will.