“Castle” Season 6 introduces its audience to Captain Gates’ family, thanks to the case in “The Greater Good.” A promo begins to show just how awkward this could be.

When a Wall Street trader is murdered, Castle and Beckett find a twist when the victim turns out to be an undercover informant for the U.S. Attorney’s office. And who is the U.S. Attorney dealing with the case? That would be Captain Gates’ (Penny Johnson Jerald) estranged sister, Elizabeth Weston (Salli Richardson-Whitfield, “Eureka”).

“Castle” will air “The Greater Good” Monday, March 24 at 10 p.m. on ABC.

Posted by:Laurel Brown