Below Zero - C.J. Box (Joe Pickett Series, Book 9)

Wyoming game warden Joe Pickett's teenage daughter, Sheridan, receives a text message with a staggering implication: that April, the foster daughter thought to have died 6 years ago in a massacre, is still alive. If it really is April who's texting, she's in danger, and for Pickett, the only thing worse than losing her the first time would be losing her again. Pickett must negotiate FBI politics, recruit his fugitive friend Nate Romanowski, and take a crash course in cell-phone-tracking technology to find her.