NCIS Season 7 Episode 23 (NCIS s07e23) with title “Patriot Down” airs on Tuesday, May 18th 2010 at 08:00 pm via CBS.
Here is summary for NCIS Season 7 Episode 23 :

Gibbs uncovers a surprising link to the crime when a colleague’s murder sends shockwaves through the team.

 Few hours after original series aired on TV, online streaming video for NCIS Season 7 Episode 23 usually available on Net and of course, if video available, as soon as possible lenidenews.com will show you where you can watch this episode for free.