Below zero - C. J. Box

In this thriller in the #1 New York Times bestselling series, a voice from the past has a chilling effect on Wyoming game warden Joe Pickett and his family.

Six years ago, Joe Pickett's foster daughter, April, was murdered.

Now, someone is leaving phone messages claiming to be the dead girl.

As his family struggles with the disturbing event, he discovers that the calls have been placed from locations where serious environmental crimes have occurred.

And as the phone calls grow closer, so does the danger.