D.V. Chernov 
Cold Trace [EPUB ebook] 

When the body of young Ben Harris is found after a Colorado snowstorm, Detective Nick Severs is drawn into a missing child case that went cold twenty years ago. As he and his hacker girlfriend Claire begin the investigation, every dark turn takes them deeper into the underworld of child trafficking and cybercrime, where danger is real, stakes are high, and where they each must decide what lines they are willing to cross in order to find justice.