I just watched Hawaii Five-0 7×01 "Makaukau ‘oe e Pa’ani? (Ready to Play?)" https://trakt.tv/shows/hawaii-five-0/seasons/7/episodes/1 #trakt
When the bodies of two serial killers are found on Five-0 property with chess pieces in their mouths, McGarrett and the team hunt for a vigilante as fear grows that tourists aren't safe in Hawaii.