Supergirl star Melissa Benoist on that 'terrifying' last scene

Warning: This article contains spoilers from Sunday's episode of Supergirl, "Deus Lex Machina."

Lex Luthor's episode-ending field trip portends grave danger on Supergirl.

The CW superhero drama's latest episode, "Deus Lex Machina," which marked the directorial debut of star Melissa Benoist, revealed what Jon Cryer's criminal mastermind has been up to since he woke up on Earth-Prime at the end of "Crisis on Infinite Earths" — from manipulating Eve Tessmacher (Andrea Brooks), whose history has changed in the new timeline, to moving the chess pieces around and pitting Supergirl (Benoist) against Leviathan. At the urging of his mother (Brenda Strong), he tried tempering his hatred for Kryptonians so he could focus on taking Leviathan down, but he ultimately succumbed to it. At the end of the hour, he discovered the location of the Fortress of Solitude and teleported right into it, which can't mean anything good for the Super Friends.

"Whenever there is a Luthor in the Fortress, it's scary, yes, but Lex Luthor stepping foot into the Fortress is terrifying," Benoist tells EW. "The entire episode we were kind of playing with this idea that Lex is an addict of Kryptonians, and that he just can't help himself but go and see what this mysterious Fortress that belongs to these Kryptonian looks like and feels like, because he ultimately wants the power they have and he wishes he was superhuman. So I wanted that to feel as ominous as possible. For the rest of the season it will come into play, and not in great ways."

While Lex was busy plotting, Kara and Lena (Katie McGrath), who haven't spoken since the 100th episode, took one step toward friendship and then several steps back. In the wake of Jeremiah's death, Lena offered her condolences to Kara, but that thaw in their relationship didn't last too long. Later in the episode, Kara used Myriad to find everyone who was trapped inside Obsidian Platinum, which angered Lena because Kara told her earlier in the season that Myriad was too dangerous for anyone to use. Of course, Benoist says there's still hope for their friendship.

"We burned a really well-built bridge, and now it's all about rebuilding and whether or not it can be rebuilt in the first place," she says. "So I would argue that things are being rebuilt, and I don't want to say too much more about it. Maybe this bridge can hold weight." Benoist laughs, and adds, "I really went far with that analogy."

Supergirl airs Sundays at 9 p.m. ET/PT on the CW.

Related content:

• Melissa Benoist explains why directing Supergirl's Lex-centric hour was 'daunting'
• Supergirl star Jon Cryer says quarantine may have changed Lex Luthor's finale fate
• Supergirl star Melissa Benoist teases 'fight for Lena's soul' in season 5