Look, up in the sky! It's spoilers!
Regular Cast: Melissa Benoist (Kara Danvers/Supergirl), Mehcad Brooks (James Olsen), Chyler Leigh (Alex Danvers); Jeremy Jordan (Winn Schott), Chris Wood (Mon-El), David Harewood (J'onn J'onzz/Martian Manhunter); Guest Starring: Tyler Hoechlin (Clark Kent/Superman), Calista Flockhart (Cat Grant), Brenda Strong (The Doctor), Frederick Schmidt (John Corben/Metallo), Rich Ting (Cadmus Doctor), Ian Gomez (Snapper Carr); Written by Robert Rovner & Caitlin Parrish from a story by Greg Berlanti & Andrew Kreisberg; Directed by Glen Winter
Things pretty much pick up where episode one left off, with the Kryptonian cousins putting out skyscraper fires and stopping thieves, one of whom is stupid enough to punch Superman after watching bullets bounce off his chest. This causes the Man Of Steel to muse, "Never understood that." He's not alone.
Two people not so amused are J'onn J'onzz and Alex Danvers, both of whom feel that Supergirl is so swept up in having fun with Superman, that she's neglecting DEO protocols. Beyond that, Alex is feeling left out, especially when Kara invites Clark to "sister night." For her part, later at CatCo, Kara is feeling lost when she's introduced to the new editor that Cat Grant has hired, Snapper Carr. He is completely dismissive and practically snorts in response to Kara's claim that reporter is the job she chose. "You didn't earn it," he replies. "You don't just become a reporter. This isn't a Facebook status update. You're a reporter because you went to journalism school or you walked the beat."
Shaken to the core, Kara actually considers following Superman back to Metropolis, believing it will allow her to find herself. But between Cat and Alex, Kara ultimately realizes that running solves nothing and that she essentially needs to find her inner strength to recommit herself to the DEO, her chosen vocation and the relationship with her sister.
The season's Big Bad reveals itself as Cadmus, an organization dedicated to ridding Earth of its alien threat beginning with Superman and Supergirl. To this end they create not one, but two versions of Metallo to take on the duo in some highly-effective fight sequences that, due to the Metallos' enhanced endoskeletons and (stolen from the DEO) Kryptonite-based hearts, allow for much more hands-on confrontations.
Eventually Cadmus comes up with a divide and conquer approach to split the cousins up to their respective cities. But the tables are turned when Winn (who has become a hybrid of Arrow's Felicity and The Flash's Cisco) has transformed DEO anti-Kryptonite technology into protective shields placed on the duo's emblems. Additionally, they are not divided, because J'onn J'onzz (in a cute bit transforming from a little blonde girl wearing a Supergirl T-shirt into Martian Manhunter) aids Superman in Metropolis, while Alex, adorned in her power suit from last season, kicks ass with Kara.
In both instances, the Metallo hearts are removed, which is followed by an interesting bit of editing. It's pretty obvious that one of them is dead as a result (no denying it from the look on his face and a bit of metallic drool spilling from his mouth), but then we see him alive on the pavement. Somebody probably realized that it was too Snyder-esque to have our heroes actually murder their opponents, and made the change.
By episode's end, things are shaken up in a variety of ways. Superman and J'onn have put their differences aside as Superman is allowed to take all of the remaining Kryptonite away from the DEO, given that some of it had been stolen (more on that in a bit); Kara actually makes some tiny leeway with Carr by writing an exclusive story about the battle with the Metallos; Cat announces that she is taking a leave of absence from the company because, like Kara, she needs to start challenging herself again; the threat of Cadmus is still very much out there, and the unconscious alien Mon-El, who had been brought to the DEO in the last episode, suddenly awakens, and he does not seem happy.
There are a lot of positives to "The Last Children Of Krypton." The effects and fight sequences continue to impress, expanding the boundaries of what can be accomplished for television; we get a moment in the Fortress Of Solitude between Superman and J'onn, which is very cool; and there's an effective deeper exploration of the relationship between Kara and Alex. The acting is never a problem, though a highlight continues to be the chemistry between Melissa Benoist and Tyler Hoechlin, which brings with it a sense of remorse that we don't know when we'll see them together again. Calista Flockhart gets some strong moments as she imparts final doses of wisdom to both Kara and Supergirl (we still don't quite understand how she doesn't know they're the same person), and, as was the case in "Legacy," there's a wonderful instance where Cat gets starry-eyed around Clark Kent. It's an opportunity for the actress to take on the countenance of a school girl with a crush, revealing an extremely endearing side of herself.
Where the episode drives one crazy is in the area of story contrivances. For starters, after Superman and Supergirl arrive in Metropolis where one of the Metallos have attacked, Supergirl heads back to the DEO, asking Winn where Alex is as she needs to apologize for not being nice lately. Really? Portions of Metropolis are in rubble, and that's what she's worried about?
Things get even sillier when Alex sets a trap for the DEO mole who has been smuggling Kryptonite to Cadmus, but she's the one surprised by the arrival of Cadmus' "The Doctor," who is in the DEO warehouse with her henchmen. How exactly does this go undetected by DEO security? And while the Doctor does slip away, Supergirl arrives to save the day, reconciling with her sister in the process. .
And here's a big one: To someone it apparently made sense that James Olsen, a photographer, is somehow taking Cat's place in her absence, and can be seen moving his stuff into her office. In what world is this logical, beyond giving Mehcad Brooks something to do? Not since Cadet Kirk made it to captain in 2009's Star Trek in record time has there been such a stratospheric promotion.