In Plain Sight Season 3 Episode 12 (In Plain Sight s03e12) with title “Witsec Stepmother” airs on Wednesday, June 23rd 2010 at 10:00 pm via USA Network.
Here is summary for In Plain Sight Season 3 Episode 12 :

Mary keeps an eye on a teen witness whose separated parents are too distracted by their own issues to pay attention to their daughter. Meanwhile, Marshall thinks a witness may have betrayed his brother.

Few hours after original series aired on TV, online streaming video for In Plain Sight Season 3 Episode 12usually available on Net and of course, if video available, as soon as possible will show you where you can watch this episode for free.