This was such a fascinating and frustrating NCIS episode, all at once.
The plot for "Damned If You Do" carried on from last week's tense beginning, with Inspector General investigator Richard Parsons gathering evidence in his efforts to have Gibbs indicted. His motivation was captured by this statement:
Parsons: I believe in upholding the law, Gibbs. And I'm tired of watching you break it.
Turned out that Parsons wasn't nearly as altruistic about the law as he portrayed himself. Tony told Gibbs about evidence they found, which proved Parsons was a sleazy narcissist who kissed upper management rings while doubling as a blackmail artist.