Supergirl finds herself imprisoned by her own sister, Alex Danvers, in the latest teaser trailer for the Arrowverse Elseworlds crossover event. The CW's shared DC superhero TV universe launched with Arrow in 2012 and later added the spinoffs The Flash and Legends of Tomorrow. Supergirl started its own run as a series on CBS, but saw its ratings dwindle off over the course of its first season. However, following the ratings success of its crossover episode with The Flash, Supergirl ultimately moved over to The CW for its second season and has been a key part of the Arrowverse ever since.

Kara Danvers and her allies have since participated in the Arrowverse's annual crossover events, starting with 2016's Invasion! and continuing with last year's Crisis on Earth-X. This year's Elseworlds will once again bring Supergirl, The Flash, and Green Arrow together for a storyline in which reality itself has been rewritten. As a result, Oliver Queen (Stephen Amell) and Barry Allen (Grant Gustin) have swapped lives, with Oliver now The Flash and married to Iris West (Candice Patton). For Kara Danvers (Melissa Benoist), however, life has changed in different but equally strange ways.

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The CW has released an Elseworlds teaser trailer that shows Supergirl/Kara imprisoned in a meta-human holding cell and being taunted by her adopted sister, Alex (Chyler Leigh). In addition to having a very different hairstyle, the Elseworlds Alex has seemingly never met Kara before and sees her as nothing more than a dangerous and "clearly crazy" meta-human. You can watch the teaser in the space below.

This particular Elseworlds-related development no doubt come as a sharp blow to Kara, whose relationship with her sister has always been part of the bedrock of her identity as a superhero. Alex was even on the plane that nearly crashed into National City before Supergirl intervened, thus revealing her existence to the world and saving her adopted sibling at the same time. The pair has since worked together to keep their city safe, with Alex operating as an agent for the Department of Extra-Normal Operations before she was promoted to its director at the end of Supergirl season 3. Clearly, however, none of that happened to the character in the Elseworlds version of reality.

While Elseworlds will force Oliver, Barry, and Kara to figure out a way to set things right, they won't have to fix reality on their own. The event will eventually bring the trio to Gotham City, in search of the fellow who may be responsible for creating Elseworlds in the first place: Arkham Asylum Dr. John Deegan (Jeremy Davies). Along the way, the three will cross paths with Kate Kane aka. Batwoman (Ruby Rose), a character who's not exactly happy about having yet another superhero-related mess to clean up. Nevertheless, assuming that everything goes to plan, Batwoman will get her own series next year and team up with Green Arrow, The Flash, and Supergirl yet again in 2019's Arrowverse crossover.

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Elseworlds begins with The Flash on Sunday, December 9, then Arrow on Monday, December 10, and ends with Supergirl on Tuesday, December 11. All episodes air at 8pm.

Source: The CW