In the episode, entitled "Losing Battles," she reprises the role of Joanna Gibson. After first meeting Violet (Amy Brenneman) in the fifth-season premiere, Joanna returns "pregnant and badly beaten, and in need of Violet's help. Joanna is a smart, successful lawyer and the ending will certainly prove that...in more ways than one."
The episode has a special start time of 10:02 PM ET/PT on ABC.
Brandt also appeared in an episode of Brenneman's previous series Judging Amy back in 2001.
She recently completed the fourth season of AMC's Breaking Bad, on which she portrays Marie Schrader. As part of that cast, she was nominated for "Outstanding Performance by an Ensemble in a Drama Series" at the upcoming 2012 Screen Actors Guild Awards. The SAG Awards will be announced on January 29.
If you missed it, you can read my Q&A with Betsy using this link.