Katie McGrath is now officially a series regular in "Supergirl" Season 2. Not only that, the official plot description for the next episode has been revealed.

According to TV Line, Katie McGrath will be a series regular for season 3 in the fall. She has been a recurring character this season, playing Lena Luthor.

Lena arrived in National City during "Supergirl" Season 2 premiere looking for a fresh start out of the shadow of evil brother Lex. Now that he is in prison, she wants to rebrand the family company as a force for good. Unfortunately, Lex is not the only evil family member Lena has to deal with.

For now, Lena appears to be on the side of good. She stopped her mother from releasing the deadly Medusa virus and turned her over to the police. And Lena's friendship with Kara only grows with every episode she is in.

Series developer Matthew Kreisberg shared some details via The Hollywood Reporter on what's in store for "Supergirl" Season 2. Kreisberg said during the "Arrow," "The Flash," "Supergirl" and "Legends of Tomorrow" panel at PaleyFest on Saturday afternoon, "Truth be told, we pitched a lot of what were going to do in Season 2 to CBS and they were very cool with the change. The change was more just in terms of us and what makes 'Supergirl' special and why is it different from the other shows."  

As for the official plot synopsis of episode 17, Spoilers Guide notes, "A large bounty is put out on Supergirl Kara Zor-El (Melissa Benoist) and aliens from far and near attack National City intent on taking out the woman of steel.  Alex Danvers (Chyler Leigh) and Maggie Sawyer (Floriana Lima) run into Maggie's ex-girlfriend, Emily (guest star Hayley Sales), who is in town for a week.  Hank J'onn J'onnz (David Harewood) gets an interesting order from President Marsdin (guest star Lynda Carter)." 

"Supergirl" Season 2 episode 17 is titled as "Distant Sun". The upcoming episode is scheduled to premiere on Monday, March 27, 2017, at 8:00 p.m. ET/PT first and exclusive on The CW. 

"Supergirl" is an American superhero action-adventure drama television series developed by Ali Adler, Greg Berlanti, and Andrew Kreisberg.