Teenage neighbors find the body of a Marine, LCpl. Korby, who apparently committed suicide by carbon monoxide; Gibbs and company investigate; Ducky promptly says that the death was not by suicide, and he soon sees irregularities. Ducky elaborates on his hypothesis against suicide, and Abby adds details. Korby was a practical joker whose pranks often displeased others; some of his tricks had caused problems within his outfit, and his fellow Marines had taken action. Tony consistently believes that Korby's wife killed him; he eventually starts to arrest her, but Gibbs stops him. Gibbs, Tony, and McGee put the right pieces together, and they bust the person responsible. Finally, Tony experiences a dental problem.