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.
In the season premiere, McGarrett refuses to listen to Danny's pleas to take it easy while recovering from surgery after the body of a serial killer is left in the Five-0 headquarters with an ivory chess piece in his mouth. When a second serial killer is found dead with another chess piece, Five-0 goes on the hunt for the vigilante as fear grows that it's not safe to travel to Hawaii. Also, MacGarrett finds comfort in talking to someone with a very special connection to the team.