Supergirl season 4 episode 21 live stream: Watch online

Supergirl finally meets Red Daughter in the penultimate installment of season 4. Read below to find out how you can watch the episode live.

A lot happened and didn’t happen on Supergirl last week.

Kara and Lena cracked the mystery of Supergirl’s doppelgänger and figured out Lex’s grand scheme, but they failed to catch Eve. Alex almost fulfilled her dream of adopting a baby, only for the mother to change her mind. Ben Lockwood injected himself with Harun-El and got superpowers but only succeeded in alienating his son. Kara decided not to reveal her secret to Lena.

Most importantly, we learned that not only is President Baker complicit in spreading anti-alien sentiment, but he is collaborating with Lex. The episode ended with him destroying the evidence that Kara and Lena found in Kaznia (please tell us they made copies) and abducting Kara. For how long has this alliance been going on? What does the president expect to get out of it? Surely, there are easier ways to consolidate power than orchestrating a war.

Tonight’s episode, titled “Red Dawn,” should provide clarification. Here is the official synopsis, courtesy of The CW:

"SUPERGIRL BATTLES RED DAUGHTER — Kara (Melissa Benoist) comes face to face with Red Daughter and the two engage in an epic battle. Determined to find a way to extract the Harun-El, Lena (Katie McGrath) turns to an unlikely source for help – Lillian Luthor (guest star Brenda Strong). Meanwhile, Alex (Chyler Leigh) realizes she’s missing parts of her memory, and Brainy (Jesse Rath), Nia (Nicole Maines) and J’onn (David Harewood) set out to track down aliens who have been abducted by Lex."

It looks like we’re in for a busy episode. With the season finale approaching, Supergirl has a lot of dangling plot threads to tie up and not a lot of time to do it. Again, though, we hope the show leaves plenty of room for quieter character moments like last week’s Alex storyline.

Of course, the main draw of “Red Dawn” is the long-delayed confrontation between Supergirl and her double. The return of Red Daughter should mean more of the Cold War-style spy antics and ideological conflict that made “The House of L” so compelling, and if nothing else, seeing Melissa Benoist act opposite herself is always a treat.

Alexis Ostrander directs from a story by Lindsay Sturman and teleplay by Gabriel Llanas and Eric Carrasco.

"Date: Sunday, May 12Start time: 8 p.m. ESTEpisode: “Red Dawn”TV Channel: The CWLive Stream: Watch live on Fubo TV. Sign up now for a free seven-day trial. You can also watch on The CW website or app."

Supergirl airs as part of The CW’s Sunday night line-up.