Don’t call it the first part of a four-part crossover event. The “it” in the previous sentence refers to Supergirl’s fall finale, “Medusa.” Every TV and internet ad touted “Medusa” as the first part of a mega-crossover connecting Supergirl with The Flash (Tuesday), Arrow (Wednesday), and Legends of Tomorrow (Thursday), pitting the CW’s DC superheroes against an intergalactic, world-conquering alien menace/existential threat, the Dominators. Unfortunately, the Dominators don’t make an appearance in “Medusa.” They don’t even get a shout out from a single character. On the plus side, we do get seven or eight seconds of Barry Allen/The Flash (Grant Gustin) and comrade-in-superhero-arms, Cisco Ramon/Vibe (Carlos Valdes), dropping into Supergirl’s (Melissa Benoist) National City apartment via a space-time portal/wormhole moments before the credits roll and a “To Be Continued … on The Flash” title card.
On its own, though, “Medusa” wraps up the Project Cadmus storyline, if only temporarily. Project Cadmus has spent the better part of Season 2 putting its anti-alien agenda into motion, turning public opinion against aliens, including Supergirl, and culminating with a plan to wipe out all aliens (Kryptonians excepted, for some reason) with a weaponized virus made by Kara Zor-El’s late father (Robert Gant) released in National City via an exploding missile courtesy of Project Cadmus’ de facto leader, Lillian Luthor (Brenda Strong), biological mother to Lex, adopted mother to Lena (Katie McGrath), the current CEO of the recently rebranded L-Corp. (As always on Supergirl, mother issues abound). But that’s not all, of course. Cyborg/Superman (David Harewood), aka the real Hank Henshaw, virulent xenophobe, and Project Cadmus henchman, keeps showing up at periodic intervals to muck things up for Supergirl and the DEO (Department of Extra-Normal Operations). He shows up at an alien nightclub to test out the anti-alien virus, gets into a fistfight with Mon-El (Chris Woods), and makes his escape. Later he takes on both Supergirl and the not-real Hank Henshaw/Martian Manhunter/J’onn J’onzz (David Harewood).
When the anti-alien plot isn’t moving forward, Alex Danvers (Chyler Leigh), Kara’s adopted sister, finally comes out to her mother, Eliza (Helen Slater), getting a pep talk in the bargain, Maggie Sawyer (Floriana Lima), finally admits that her “Let’s be friends” line really isn’t going to work long term, and Mon-El begins to admit he has feelings for Supergirl. She, of course, can’t quite see it, even after Eliza points it out to her during the friends-and-family Thanksgiving dinner that opens the episode. Alex almost comes out to Eliza right then and there, but a space-time portal puts a temporary block on her plans. Likewise with James “I’m the Guardian, Damn It” Olsen (Mehcad Brooks) and his armorer-in-chief, Winn Schott (Jeremy Jordan), and their plan to confess their vigilante ways to Kara and maybe do the superhero thing together (that and feeling guilty over lying to Kara repeatedly).
That’s one plot thread, though, that Supergirl’s producers decided to leave unresolved until Supergirl returns from its mid-winter hiatus in January, probably because it’s a minor one, especially considering it was (and is) meant to give Olsen something to do now that the Supergirl-Olsen romance has been relegated to the back burner. (Time will tell whether it’ll be permanent or not.) Not that most of Supergirl’s fans will remember or even care in two months time. What matters in the here and now is what part Supergirl will play over the next three nights on the CW’s super-special crossover event. All evidence points to something more than the disappointingly brief cameo the Flash and Cisco made on”Medusa.” They might not be the Justice League of America or even the Justice Society, but by the time Legends of Tomorrow rolls around Thursday night, we should have the next-best-thing, a small-scale superhero team-up a year before their big-screen counterparts fight an existential threat of their own.