“Legion of Super-Heroes” is episode ten of season three of Supergirl.
In the previous episode, “Reign”, Supergirl was badly beaten by Regin. Kara wakes on her bed in her loft and there’s a knock on her door. She opens it to find a blue alien with glowing discs in his head. He says he’s Brainiac-5, half computer, half organic. Mon-El sent him. Kara’s brain is truly in remarkable health for someone in a coma. Brainiac-5 – ‘Brainy- – explains she’s been in one for two days. Mon-El woke Brainy up to communicate with her through 31st century tech. Which is also keeping her alive. Kara remembers and decides she has to leave to stop Reign. She can’t.
Supergirl in in a healing tube with the others around her. Brainy says the good news is her mind is active and alert. The bad news is she’s very angry. Mon-El says Kara is through the worst of it and will live, but doesn’t know when she’ll wake up. J’onn is worried about Reign.
Sam is playing with Ruby, when Ruby leaves. Sam sees a photo of Reign and Supergirl in the paper. Reign is in her fortress being congratulated and told that the world needs cleaning, not just of sinners, but those who harbour them. Reign is to show them what justice really is.
Lena joins James at CatCo. She asks about Kara and Supergirl. She also wants them to talk to Kara about Lena and James kissing. Then Reign crashes through a window with a thug and wants a camera turned on. The man was a thief and was condemned by his own actions. Those who looked away will be punished in kind. No more mercy, only justice. Reign states she’s there to help.
At the DEO, they’re watching and trying to decide what they can do/. Mon-El says the Legion can’t help, because if they die now, it would endanger the future. They do know that Supergirl lives and that eventually Reign leaves, but not much more. In the 25th century there was an extinction event that resulted int he loss of most history and culture. Mon-El taught them everything. But there are gaps. J’onn orders the Sundown Protocol, intended to deal with a rogue Kryptonian.
Alex wants to talk to Thomas Colville first. However, he says Reign has already won and that Supergirl failed in her task. Reign will prepare them for what comes next.
James and Lena are talking about CatCo. He’s worrying about Kara, but can’t say why; she thinks he regrets the kiss. He ends up having to say Kara has the flu. And Lena decides to go and see her. Awkward. James calls Winn for a favour.
Brainy is checking Kara’s loft for signs of brain damage. In order to prepare her for re-entry. Yes, she’s ready to wake up. However, though Kara is better, she doesn’t wake.
There’s nothing wrong with Kara now, but she’s still unconscious. Mon-El wants to help, but is worried about the future. And Reign is more powerful than any ordinary Kryptonian.