There are several possibilities:
* You might be thinking of a different show: Perhaps "Under Covers" is an episode of a different crime drama or series. Please double-check the show's name.
* You might be misremembering the episode title: There are many episodes of NCIS with similar themes or storylines. Could you remember any details about the episode you're looking for (e.g., the plot, the characters involved, or the season)?
* The episode title might be "Undercovers": There is an episode of NCIS called "Undercovers" (Season 8, Episode 14). This episode involves a case of counterfeit money and a mysterious woman who disappears.
If you can provide more information, I can help you identify the episode you're looking for.