Hostile Internal Affairs detective Rex Coughlin and his moderate partner Nicholas Cruz grill Chin and his Five-O partners after a slow torture murder is ascribed to Mexican cartel baron Gabriel Waincroft. He's the cousin of Chin's late wife Malia, and unproven suspect of the murder of her father during a shop robbery 15 years ago, when Chin completed police academy. Attempts to solve the case kept failing, but Chin is blamed for several unprofessional decisions and suspected of complicity or even murder. Returning to Hawai, Gabriel, once a drop-out loser desperate to join a local gang, took a child hostage to force a widow to clean up her murdered drug accomplice husband's safe deposit box, but Five-O was on his tail.
—KGF Vissers