Melissa Benoist is really good at crying, y'all. I've seen it said that Benoist's performance as Kara Danvers/Supergirl is what truly props up Supergirl. When a season has been weaker, as this one has, that sticks out even more. This week, the roiling undercurrent of Kara and Lena's relationship comes to the surface, and so does the mysterious, unspeakable threat plaguing planet Earth, known only as Leviathan. Spoilers follow for Supergirl Season 5, Episode 7, "Tremors."

"Tremors"

In the last few weeks, we've watched the collective team try to understand Leviathan. Meanwhile, J'onn has tried to cope with his feelings of guilt over having erased his brother, Malefic, from the Martian collective consciousness. Alex and Kelly continue to struggle for a positive relationship despite the huge amount of trauma both have seen. And underneath all of that, Lena Luthor has her own plans. A lot of that comes to a head this week. The dual emotional cores of Lena/Kara and Malefic/J'onn work well together, though I'm not quite as enamored with the rest of the episode.

Leviathan finally reveals itself. Where in the comics, Leviathan is a criminal organization led by a human being, Leviathan here is something else completely. The show adopts the same trident-chalice symbol that we've seen in DC's Event Leviathan, but the two are otherwise wildly different. The Leviathan of Supergirl is a small cabal of immortal aliens from a "sister planet" of Krypton who have been controlling the development of planet Earth behind the scenes since before humanity existed. Brainy digs up all kinds of historical records that point to a single person being present at countless catastrophic disasters.

That's the impetus for Kara to bring Lena into the fold, and Lena suggests that weapons that kill Kryptonians will be useful against these beings. That's enough for Kara; she's eager to share the previously-hidden side of her life with her best friend, including the Fortress of Solitude where all those weapons are kept.

Oh, Kara.

Two different resolutions

Meanwhile, J'onn is communing with his deceased father as he tries to find a way through the guilt consuming him. The Martian race is a collective consciousness that shares memories and absorbs the memories and personalities of the Martians who have passed. In speaking with his father, J'onn comes to realize, first, that he feels his brother nearby because his brother is nearby. He also comes to understand that the one thing he hasn't tried yet is to simply drop his guard and open himself to a "bonding" with his brother. Think of it like a Martian mind-meld instead of a Vulcan one. And so, taking the rigged Phantom Zone generator that sent Malefic to Lena's lab instead of to the Phantom Zone, J'onn goes to his brother and drops to his knees, giving Malefic plenty of chance to kill him.

Superbetrayed

The two stories play out very differently. Kara eagerly shows her friend around the fortress while her friend sets traps behind her back. It's not until Lena lays her eyes on Myriad, the device the Kryptonians of Supergirl season 1 used to exert mind control over humanity. I'm still sad that the Supergirl has decided to make Lena a villain, but I'm starting to believe it.

The venom in her voice as she comments on what a good actress Kara's been throughout their friendship is impossible to miss. And I genuinely believe that Lena didn't intend to out herself to Kara at the moment she chose. It was Kara walking in on her with Myriad in her possession that forced Lena's hand. As Lena lists off her many small betrayals, it's easy to get swept up in it and believe it, even though we know Kara was trying to protect her friend—even if her friend didn't need protecting.

Lena turns the Fortress' security systems on Kara, the look of hurt in Kara's eyes is heartwrenching. Both actresses did an incredible job with this scene, and it set up a very different path ahead for Kara. The optimistic hero is now faced with having to accept that not only is the woman she thought was her best friend a very dangerous person but a dangerous person who knows her secret identity. When Lena jumps through her portal while Kara watches, trapped in what is supposed to be a safe place, it's hard not to feel an absolute chill. This is easily one of the strongest moments of the season in terms of both acting and emotional payoff.

Martian Mind-Meld

Back in National City, Malefic bonds with J'onn. As Malefic brings his forehead to J'onn's, it looks more like the start of a headbutt than a mind-meld. But J'onn's memories and feelings flood Malefic's mind, and he absorbs not just J'onn's emotions but those of his father. All at once Malefic understands the impossible situation their father put J'onn into, and how that situation made him feel. It's hard to tell for sure if Malefic is being honest, but it feels like it's real as the two brothers embrace. If Malefic's campaign of revenge is over, a Martian team-up could be in the works. But we also shouldn't forget that a Crisis is coming.

While all this is happening, Brainy has had an epiphany. After the initial run-in with Leviathan sends Kara and Lena off looking for weaponry, Brainy and Alex are investigating things more locally. An assassination attempt by Leviathan ends up accidentally unlocking some of Brainy's processing power, and he concludes that Leviathan exists in National City, because of course it does. Leviathan just isn't very interesting right now, though. It doesn't have the same visceral appeal that Agent Liberty did. Each move by Liberty put Kara and her team in a more and more impossible place. Instead of a problem they can't solve with their fists, the team now has a mystery that will inevitably be solved through some pseudo-science mumbo-jumbo rather than through any substantial character development.

High stakes, low interest

Best case scenario here is that Leviathan becomes a reason for Kara and Lena to work together, and maybe even for Lena to see the error of her ways. Right now, though, Leviathan (which features actress Cara Buono, Nancy Wheeler's mom, Karen, from Stranger Things) is just another generic alien cabal with designs on controlling Earth. They're no different from the Daxamites or the Kryptonians we've seen in previous seasons.

Hopefully, the conflict between Kara and Lena comes together well enough to hold up the season, because Leviathan definitely isn't thus far.