During the surveillance of a cheating husband, Catherine is shot and Billy is killed. When Catherine returns to the cabin, there is no evidence a murder was committed. They track the victim's burner phone to find the body. Joe helps crack the encryption on the victim's computer and it reveals that he was selling classified information to a competitive company. The head of the competitor admits that they cleaned up the murder, but they didn't commit the crime. A bullet leads to a hit man, and Chin is able to track an IP address to the person who hired the hit man - the assistant to the prostitute who was sleeping with the victim. McGarrett asks Joe to help him find Doris. Adam gives himself up to the Yakuza to give Kono time to get away, but she won't leave without him.