Hawaii Five-0: Season 8, Episode 3

8 - 3: Kau pahi, ko'u kua. Kau pu, ko'u po'o (Your Knife, My Back. My Gun, Your Head)

Five-0 enlists the help of an old friend when the boss of a major crime family is murdered, triggering revenge killings across the island. Also, MacGarrett and Danny begin sorting out particulars in their new restaurant venture.