[This is a review of Supergirl season 2, episode 7. There will be SPOILERS.]

Since the beginning of season 2 -- and the show's soft reboot as a result of shifting from CBS to The CW -- Supergirl has been diving into the theme of aliens as refugees on Earth, tackling the topic by showcasing the many ways aliens are viewed by humans, and how aliens view each other. Although anti-alien sentiment is widespread in Kara Danvers' home of National City, it's largely represented in Supergirl by the organization called CADMUS.

Throughout the early part of Supergirl season 2, CADMUS has thrown a number of antagonists at the Girl of Steel, ostensibly to prove to the public that aliens and alien technology shouldn't necessarily be trusted. Ranging from the two Kryptonite-enhanced Metallo warriors in the second episode of the season, to the more recent human antagonists outfitted with alien weapons, CADMUS has facilitated many threats to Supergirl so far. Now, CADMUS reveals another villain from the organization's stockpile: Cyborg Superman.

In this week's episode, 'The Darkest Place' -- written by Robert Rovner and Paula Yoo, and directed by Glen Winter -- Kara faces off against Cyborg Superman (whose identity was seemingly revealed earlier today) while attempting to rescue Mon-El from CADMUS. Elsewhere, James' new vigilante alter ego, Guardian, comes under fire when he's framed for murder and the National City Police Department issues a warrant for his arrest.

Jeremiah Danvers (and Cyborg Superman) Revealed

Supergirl Darkest Place Melissa Benoist Chris Wood

Supergirl's capture by CADMUS offers a number of reveals that fans of the series have been waiting for since Project Cadmus was first introduced in season 1. While season 1 left the secret organization a loose thread as the show looked to wrap up the villainous thread of Non andn Myriad, season 2 has developed a slow unraveling mystery the storyline would have lacked if pursued in the back half of Supergirl's freshman outing. That said, 'The Darkest Place' offers two major reveals that may have been better suited to being split up.

When Kara is lured to CADMUS in an effort to save Mon-El, she is faced with the alien-hating human Hank Henshaw, who has been transformed into Cyborg Superman. His and Kara's fight is brutal, proving he is an equal match to the superhero and giving their dynamic real stakes. In a nod to the comic book character, Kara burns off part of Hank's face around his left eye; while the scene is enjoyable in its comparative subtlety, the following moment in which Hank cheesily states, "I'm Cyborg Superman," goes full-blown caricaturish villain.

Still, for all Cyborg Superman's villainy in the scene, he's largely ignored for the remainder of 'The Darkest Place', appearing briefly at the end taking the vial of Kara's blood to the Fortress of Solitude in order to gain information about Project Medusa. Rather, the episode's bigger reveal turns out to be that of Jeremiah Danvers (Dean Cain), alive and well in CADMUS -- where he reveals he's been for the past 15 years. The heartfelt reunion between Kara and Jeremiah is sweetly sentimental, especially when Kara worries over what Alex will think if she doesn't rescue the Danvers patriarch.

Of course, Jeremiah's return is necessary to moving the story forward, as well. After Kara is forced to solar flare (rendering her essentially human) in a deal to save Mon-El's life, she and the Daxamite, who is weakened by a lead bullet in his leg, are both without powers and at the mercy of CADMUS -- while their friends have no idea the heroes are even missing. Enter: Jeremiah, back from the dead.

But, with Kara's adoptive father forced to quickly remove the bullet from Mon-El's leg and urge Kara to leave, there is little time left for explanations, despite plenty that needs to be explained. Given Jeremiah's ties to both Kara and Alex, as well as the mystery currently surrounding the character (for instance, what has he been doing for the past 15 years?), his return is a highlight of the episode. As a result, Jeremiah upstages the less compelling introduction of Cyborg Superman.

Guardian v guardian

Supergirl Darkest Place Jeremy Jordan Mehcad Brooks

Meanwhile on Arrow, James is put in a difficult position when a new vigilante in National City begins impersonating Guardian and leaving a body count in his wake. With Kara otherwise occupied, clearing Guardian's name falls to James and Winn -- and Alex once she (easily) gets the truth out Winn. Guardian's storyline in 'The Darkest Place' gives the show a chance to explore where vigilantes fit within the world of Supergirl, and gives the shows' writers a chance to reference a vigilante with too many gadgets.

However, while Guardian offers both James and Winn a more compelling story/character arc than their romantic relationships with Kara as in season 1, this particular plotline feels out of place on Supergirl -- and more in line with other shows in The CW's DC Comics universe. Certainly, there is potential for James' Guardian arc to tap into the theme of aliens-as-refugees, and how that may leave humans feeling powerless (a theme Zack Snyder explored in Batman V Superman: Dawn of Justice). But, with the Guardian impersonator seeking revenge on criminals who were released from prison on technicalities (i.e. human error), this particular storyline is extraneous to the alien throughline of Supergirl.

The only relevant part of this plot is that Alex learns Guardian's identity from Winn -- which then leads to Alex confronting Maggie about the status of their relationship. Though tangential to the Guardian storyline, Alex's journey and her relationship with Maggie relationship has shined many times throughout season 2, and their scenes in 'The Darkest Place' are again some of the most compelling of the episode.

The Martian Divide

Supergirl TV Miss Martian Reveal

Rounding out an episode of largely disparate storylines, J'onn spends much of 'The Darkest Place' realizing something isn't right with him since receiving the blood transfusion from M'gann in last week's episode. After admitting to Kara he's had visions of his family -- and the pair sharing a sweet bonding moment as survivors -- J'onn fails to tell Alex what his strange blood work means. Rather, J'onn confronts M'gann on his own and forces the White Martian to reveal her true self.

Though this storyline, and especially the scene in which J'onn confronts M'gann, have plenty of emotional resonance, it isn't necessarily given the opportunity to shine. Since 'The Darkest Place' is stocked with so many revelations, J'onn learning M'gann's identity doesn't quite hold as much weight when it's relegated to the C-plot of the episode. Still, with M'gann telling J'onn the White Martian blood in his system is slowly turning him into the thing he hates, this storyline has plenty of potential going forward.

All in all, 'The Darkest Place' dives back into the overarching storyline of Supergirl season 2 -- unraveling the mystery of CADMUS a little further, revealing Lillian Luthor (Brenda Strong) to Kara, and perhaps teasing the organization's plans. Plus, Lillian reveals her personal motivation behind CADMUS to be her son -- imprisoned after Superman supposedly betrayed Lex -- though there's undoubtedly more to unpack in that history. With Guardian still establishing himself in National City and J'onn now holding M'gann captive, 'The Darkest Place' also provides setup for what will hopefully be compelling payoffs in later episodes.

First, though, Supergirl kicks off the four-show DC TV crossover next week -- which entails Barry Allen (Grant Gustin) and Cisco Ramon (Carlos Valdes) paying a visit to National City.

Next: Supergirl - The Green/White Martian Conflict Explained

Supergirl continues Monday November 28 with ‘Medusa’ at 8pm on The CW.