Up until now Kara has been sure of her family's past but on the Dec. 14 episode of "Supergirl" her loyalty will be tested by none other than her own aunt.

According to the newly released promotional trailer for Episode 8 of the series, called "Hostile Takeover," Kara's (Melissa Benoist) villainous aunt Astra (Laura Benanti) will make Kara rethink what the young hero thought she knew about her mother.

From flashbacks through out the series, fans know that Kara looked up to her mother who worked in Krypton's government. It was because of Kara's mother that Astra was sent to Fort Rozz.

Since Kara's mother died when Krypton was destroyed, Astra, who has a plan to take over earth, will use Kara to get her revenge regardless of the fact that they are family.

Also dealing with drama is Cat (Calista Flockhart), whose in danger of losing her job as CEO of CatCo because personal emails containing private material get leaked and threaten her reputation, reported Comicbook.

The episode will most like end with a big bang or cliffhanger since it will also serve as the winter finale. The series recently received a full order and will continue on after the winter break with 12 more episodes.

CBS announced a new casting for when the series returns. Italia Ricci will be joining the cast as Siobhan Smythe, who also happens to double as the villain named Silver Banshee.

Smythe will make Kara's life at work much more complicated by threatening her role as Cat's assistant and eventually challenge Supergirl. She uses her ability to release lethal wails and travel through sound waves to cause problems in National City.

Previously to getting casted on "Supergirl," Ricci starred in ABC's "Chasing Life" as April Carver. Ricci will make her first appearance on Episode 14 of the series.

Check out the trailer and catch Episode 8 of "Supergirl" on Monday Dec. 14 on CBS.