It’s Thanksgiving at Kara and Alex’s beautiful loft in National City, and once again, they’re having Friendsgiving. Winn and James are clearly angling to reveal their Guardian-related nighttime activities, but Alex thinks it’s a bad idea…maybe because she’s got her own bombshell to drop: She’s getting drunk to work up the nerve to come out to her mom over dinner. Mon-El’s there, too, and he’s Eddie Haskelling at Eliza, trying his best to pave the way to courting Kara. Eliza totally sees this, but Kara claims not to. For a girl who can literally see through walls, she’s oddly blind about what’s right in front of her. But they’re all distracted from their personal dramas by a tiny wormhole flashing in midair over the dinner table.
But enough about mysterious portals and personal revelations, let’s talk about Cadmus. The DEO gang agrees the top priority is figuring out what Mama Luthor is up to. Kara helpfully suggests that she could interview Lena Luthor and be “sneaky” to get her to talk about mom. Kara is not good at sneaky. She gets nothing out of Lena except awkwardness. Lena is definitely smart enough to know Kara’s got a motive beyond “profiling successful women and talking about their mothers,” so she immediately calls Lillian to ask WTF.
Over at the ever-popular alien bar, Mon-El is having a quiet beer when he spots a very suspicious figure…it’s Hank Henshaw, aka Cyborg-Superman! He’s planted a device under the bar, and just after Mon-El follows him outside, the device starts billowing smoke.
Mon-El challenges Henshaw, and Henshaw basically cleans his clock. Incidentally, Henshaw is wearing a kind of Phantom of the Opera mask, covering the cyborg facial structure section left bare by Kara’s eye blast last week. It's kind of cool-looking, and it no doubt saves a ton on the effects budget. Good thinking.
Mon-El hears screams, so he rushes back into the bar to try and help. It’s too late, of course, and the aliens are all dead. The humans are fine. Mon-El only caught the tail end of the smoke bomb, so he’s not dead…but the DEO puts him in isolation just in case. Kara hangs out to sort of flirt awkwardly through the glass, and it’s so painful. What’s up, Kara? He’s so cute and cool, and you’re only going to have a little while before he has to leave the planet, so get a move on! (That we know he's not long for this world, and she does not, only adds to the pathos.)
Mon-El collapses and is moved to the medical lab, where Eliza is helping out. The virus is identified as Kryptonian in origin…Kara realizes Cadmus stole her blood in order to infiltrate the Fortress of Solitude. She goes to learn more about this virus, and she has a convo with her holo-dad, which basically breaks her heart by proudly acknowledging that the virus was his own creation. He built a virus that would attack aliens only, not Kryptonians so that they could use it in the war at no risk to their own people, and with no property damage. (My husband asked why it doesn’t kill humans. Cadmus clearly tinkered with the formula before releasing it, is my explanation. Do you have another theory? Share it in the comments!)
Back at the med lab, Alex finally has the talk with her mom. Eliza is awesome, and it’s a terrific scene. This is a really solid coming out story, and I’m glad to see it told so well on such a great show. Bravo, DC & The CW!
Another awesome conversation is happening out on the balcony, where Kara is sharing her pain with J’onn, telling him her dad was engineering genocide. J’onn plays devil’s advocate, pointing out that he was working to protect his people, and Kara points out that Lex and Lillian Luthor have the same reasoning for why they’re the good guys. It’s moments like this where you know the heroic path is absolute, and you grudgingly acknowledge Kara was right not to murder Lillian and her henchmen last week, even though it would have been SO EASY and totally reasonable…it would have been the wrong choice for a hero.
The virus, Project Medusa, is missing a crucial component that would make it easy to disperse over a large area like National City. The missing piece is a manmade element, Isotope 454, and it’s made by one company: L Corp. Kara realizes Cadmus will attack there next to acquire it. She goes in, fights Henshaw again, and saves Lena again. Maggie shows up to help and is injured, probably because another wormhole distracted her. Man, Cisco’s having trouble with his Vibe mojo.
Henshaw didn’t get what he needed in the L Corp fight, but Cadmus certainly won’t stop trying. It’s time to talk to Lena again, but this time, Supergirl shows up instead of Kara. It doesn’t seem to be going well…the Luthor persecution complex flares up. Lena accuses Supergirl of treating her just the way Superman always treated Lex. As soon as Supergirl is gone, Lena’s on the phone to her mom.
Alex is sewing up Maggie’s wound, and she tells Maggie all about how she’s happy with the direction her life is taking, she’s realized it wasn’t really about Maggie, it was all about her own journey, basically that she’s over Maggie. Maggie’s puppy dog eyes tell a different story.
Speaking of puppy dog eyes, Mon-El is still at death’s door, but he wakes up and kisses Kara before passing out again.
Winn has a sensor configured to notify them when Isotope 454 is on the move. It’s en route to the port, where Cadmus intends to launch the virus over the city. J’onn refuses to stay behind, though the virus would kill him; he’d rather die on the job than keep turning into a White Martian.
At the port, Lena snarls at Supergirl about being a Luthor and doing what Luthors do, then fires the missile. Supergirl fails to think of eye blasting the control console before Lena turns the key, but chases after the rocket. J’onn goes full White Martian to kick some Cyborg-Superman ass.
Supergirl catches the missile, but too late–it explodes in her face! Lillian Luthor is triumphant…but J’onn is right in front of her, and he’s not dying. She realizes Lena played her. Good girl, Lena! I guess Kara’s judgment of people is pretty solid after all. Lena not only swapped out the element with something that killed the virus, she also ratted mom out to the cops.
Now that the danger has passed, Eliza is able to use a sample of the virus to generate an antidote. Mon-El is cured! Eliza has also developed a treatment for J’onn, using the Medusa virus to attack the White Martian blood cells. J’onn is Green again! Mon-El and Kara wuss out on even addressing their spark and the kiss.
But Maggie doesn’t wuss out this time! She shows up on Alex’s doorstep with pizza, beer, and a kiss. It’s nice. Good for Alex.
Finally, it’s the start of the crossover! The wormhole opens up for real this time, and out pop Barry and Cisco. Barry introduces Cisco as his friend, and Cisco tells Kara, “Friend is a loose term,” identifying himself as more of a coworker. Harsh, Cisco! That made me sad. Anyway, they need Kara’s help back on Earth-1, where they have an alien problem.
Speaking of aliens, there’s a spaceship full of people who want to find Mon-El, and it doesn’t seem like they want to recruit him to their intramural Quidditch team.