Junior and Tani watch a Betamax tape sent to Five-0, on which is recorded a murder. Dani points out to McGarrett that Adam left home that same day as Noriko was found dead. Harry Langford is in town providing security for British royals visiting Hawaii, especially the rebellious Lady Sophie. Sophie runs away while shopping for clothes. Tani and Junior bring the tape to Grover. He suggests they find the motel where the murder took place. Harry, McGarrett and Danny track down the car Sophie took from the store. The hotel key in the video is to Room No. 13. Harry calls Sophie's best friend, Carlotta, who said he met a boy there on a dating app. Junior and Tani track down the right motel. They go into the attic above the room, and Tani chips through the ceiling from the old air vent. Danny finds Sophie's male friend on social media, then they go crash his party. Harry leans on Travis to find out where Sophie is. Sophie left the party with two blonde girls. Harry grabs a paparazzi's camera to look for clues, then deletes the photos. Tani figures out who the murder victim was. Junior finds the peeper, Arthur Dubbins, who is hospitalized with a stroke. That man's wife, Alice, sent the tape to the police. Grover appeals to her for help. Alice showed them Arthur's collection of peeper videos. The girls take Sophie to a boat. From the video, Grover figures out the killer was an airline pilot. Sophie has been taken to be sold into the sex trade. Sophie wrote the boat's name on the back of the car seat for Harry and McGarrett to find. Harry and McGarrett quickly empty the boat of bad guys. Grover and Tani arrest the pilot. Harry is actually Sophie's father.