McGarrett stops David, a Japanese man, from murdering a Pearl Harbor veteran at a remembrance service. David accuses the veteran of killing his father and stealing the family's priceless katana. David recounts his internment story as Five-0 investigates the murder. Army reports are incomplete and compromised, but evidence from a homicide cop's handwritten records leads the team to the brother of head guard at the internment camp. They successfully recover the katana. Meanwhile, McGarrett is emotionally caught up in the case when he learns David's family has ties to his grandfather.