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.
Tani and Junior must plot an escape for themselves and several civilians after they become trapped inside a deadly tunnel collapse, while Five-0 investigates the cause and culprits of the cave-in. Eddie the dog uses his field experience and sniffs out a bomb that has been planted in McGarrett’s home.