S10E21: A ʻohe ia e loaʻa aku, he ulua kapapa no ka moana (He Cannot Be Caught for He Is an Ulua Fish of the Deep Ocean)

After Steve receives a posthumous letter from his mother that contains a cypher, Danny is attacked by someone willing to kill to steal it. Five-0 must help Lincoln Cole, an anonymous good Samaritan who’s in the crosshairs of some very dangerous people.