The Five-0 team investigates the murder of a wealthy Hawaiian couple. The victim's brother reveals that he sold the alarm code. Photo evidence reveals a missing artifact called a scrimshaw. Chin realizes the scrimshaw has a crest from The Royal League, an Illuminati-type group in Hawaii, and the team enlists Jerry, a conspiracy theorist, to uncover the secret of the scrimshaw. Jerry believes the scrimshaw is a key to where The Royal League hid a set of rings from Italy and evidence reveals that the rings are hidden in the King Kamehameha statute. The team quickly realizes that the suspects replaced the original statue with a fraud, and Catherine helps decode a series of letters which confirm the rings are inside the statue. McGarrett and Danny track down one of the suspects and he reveals the key wasn't at the couple's house. Five-0 stops the suspects from stealing the scrimshaw from a museum. Jerry is allowed to open the statue. Meanwhile, Catherine leaves the Navy.