CBS' hit series Tracker has lost three cast members before season 3 - but what has the show's lead and executive producer Justin Hartley said about the ongoing changes? Hartley is the reason many Tracker fans started watching the show when it premiered in February 2024. Following a six-year stint on NBC's This Is Us, Hartley scored his own show, which introduced fictional survivalist Colter Shaw as he travels the country to help solve various missing persons cases.