 A respected physician on a remote island is found dead, and an autopsy reveals he was blown away with a shotgun while night swimming. The only suspect is a young-Turk doctor at a local clinic, who was convinced the old doctor had botched operations and killed people. But when other people s stories turn up inconsistent, McGarrett realizes the old man was covering for a series of shady financial transactions and was killed -- by someone else -- because he knew too much and was blackmailing somebody to hang onto his job. The killer is not revealed until late in the show; a good fistfight in a horse barn caps this episode.