Chin Ho is kidnapped and wakes to find himself trapped in Halawa prison disguised as an inmate. With no time to waste, the team must bypass the rules to save Chon Ho’s life.

When threats turn deadly against a tour company that endangers the local shark population, Five-0 faces the difficult task of narrowing down the suspect list. Meanwhile, the team debates whether or not Kamekona will earn his helicopter license.

An investigation involving a potential serial killer puts Chin's life in danger; Grace and Danny find a mysterious puzzle box.