Five-0 investigates when a plane that mysteriously crashed into the Pacific in the ‘80s is found, but with a recently murdered scuba diver inside. Also, as MacGarrett and Quinn zero in on who planted the bomb in his garage, and he formally asks her to join Five-0, she is arrested for money laundering.

It's Halloween and Five-0 investigates a home invasion turned deadly after a dangerous "monster" escapes from the basement. Also, Max returns to Oahu with a very special guest.