This week on Supergirl Kara struggles to save not only her boyfriend and best friend, but the entire city from the Daxamite invasion.

Last week, Rhea opened a portal and Daxamite ships appeared over National City. She escaped and transported Mon-El and Lena with her to a ship.

“Resist” opens on Rhea waking Lena on the ship. Lena remembers what happened and is understandably upset. Rhea explains she wants Lena to be a part of her new world as the two watch the Daxamites attack the city. Rhea’s voice and image echoes throughout the city, telling people she is their new ruler. Maggie fights the aliens and calls Alex, who also ends up fighting Daxamites when they transport into the DEO. Alex evaluates the DEO and calls Supergirl for help. Alex runs and flips off of the balcony, taking down one more alien as she plummets. Supergirl grabs her just in time as Rhea welcomes the city as a new Daxam.

On the ship, Mon-El asks his mother about her plans. She wants to create monuments to their people, which humans will build. Mon-El exclaims the humans will fight back, as will Kara. Rhea ignores his warnings and tells him he will marry a human to connect the two peoples. She has chosen Lena for his wife.

Kara, Winn, Alex and a handful of DEO agents set up operations in the alien bar. J’onn is there, but he is still unresponsive after the fight from the last episode. James walks in, letting them know how bad it is outside and the team discusses how they have not been able to find Superman. Maggie arrives and the team tries to figure out where to start when Lillian Luthor shows up. She tells Alex she does not know where Jeremiah is and says she wants to team up to fight the aliens, saying she knows a way onto the ship. The group strongly declines. She pleads with Supergirl, calling her Kara so Lillian knows who she is, to help her save Lena and tells her to contact her if she changes her mind.

Back on the ship, Rhea receives a message from U.S. President Olivia Marsdin, demanding the Daxamites leave. She tells them she is coming to fight her with the military. The two argue and Cat Grant walks into the room with the President and tries to talk them down, but also insults Rhea but introduces herself as “queen of all media.” Rhea ends the conversation and attacks the plane. Winn picked up the signal and aired the showdown between Cat and Rhea for Kara, who immediately flies to save Cat and the President. Supergirl is able to grab Cat before Air Force One breaks into pieces. On the ground, the President pushes a piece of the plane off her body while in her alien form, thus revealing herself to Cat and Supergirl.

Supergirl brings the President and Cat to the alien bar. Winn hugs Cat and she asks about all the DEO agents and equipment. They tell her the DEO exists and she tells them about being in Washington D.C. when the Daxamites invaded. President Marsdin was her RA in college, and she tells them about a night she saw her alien face and thought it was just because she was high. Winn laughs until the President walks out as an alien. Cat shrugs off the fact that her friend is an alien and walks off to take a call with Madeleine Albright, making a quip about Bill O'Reilly.

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The President sits down with the team and tells them she is from the planet Durla, which was invaded and people were enslaved. She reminds Alex she is now the head of the DEO with J’onn still in a coma. Kara tells her they have civilian friends on the ship, but she tells them to get a positron cannon from the DEO headquarters to destroy the Daxamite ship.

On the Daxamite ship, Lena and Mon-El tell Rhea they are not getting married. Lena tells her they are not having a child, but Mon-El tells her Daxamites can create a child with their hair, which Rhea already took. Rhea threatens all the hospitals in the city. The two reluctantly agree to have the wedding ceremony.

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After sending the President back to the White House, Alex and Kara argue over using the cannon. Alex tells her even if it was Maggie on the ship, they have their orders. Kara walks outside as Supergirl and finds Cat sitting by a dumpster Cat thanks her for saving her life and asks her who is on the ship. Supergirl replies her boyfriend and best friend are on the ship and she will be devastated if she loses them in this fight. Cat tells her she left the city because she was unhappy and went to Bhutan, because her phone said it is the happiest place in the world. She talks about the people and what she learned was happiness is connecting with other people. Telling her, “It’s not about what you do, it’s about who you love.” Cat tells her she is not selfish and to go save the people she loves. Kara listens and goes to team up with Lillian.

Photo: Robert Falconer/The CW -- © 2017 The CW Network, LLC. All Rights Reserved

Alex is annoyed that Kara teamed up with Lillian, but the group works on a plan. They have a way of beaming on the ship. Alex and the DEO agents will work on getting the cannon from headquarters. They need a distraction for Rhea and Cat volunteers, asking for Winn’s help. The sisters say goodbye to each other, Alex telling her she would do the same thing for Maggie. Alex tells her to be as fast as she can.

Kara, Lillian and Hank go to the Fortress of Solitude. Kara asks why Lillian never told Lena who she is and Lillian says Lena will find out and hate her when she does. Hank fixes the portal and they beam to the ship where Lena and Mon-El are at the beginning of their marriage ceremony.

Cat looks around CatCo and is more upset about the free weights and sports items in the office than the destruction of the office. She asks Winn where James and Kara are and he lies saying they are in hiding.

Alex and Maggie work on breaking into the DEO together, Maggie reminiscing about how they first met. They get in and find the cannon and start charging it to fire. The President tells her to fire when it is ready.

The marriage ceremony is almost complete when Cat’s broadcast starts airing. Cat tells the people to fight back against the invaders, to resist. Rhea is angry and sends a group to kill Cat. On another part of the ship, Supergirl battles Daxamites while Hank works on finding Lena.

Meanwhile, Mon-El picks a fight with a guard and Lena picks up his gun and saves Mon-El. Lena picks the lock to one of the doors and when the door is open they meet Supergirl. Lena's happiness at her mother working with Supergirl is short lived when Lena is the only one transported with Lillian and Hank. Lillian calls Alex and tells her they are free and to fire on the ship. Lillian is confused when Lena is angry with her and wants to save Mon-El and Supergirl.

Photo: Robert Falconer/The CW -- © 2017 The CW Network, LLC. All Rights Reserved

On the ship, Kara tells Mon-El she thought something like this might happen so she has a device that will turn the tech back on. Kara sends him back, telling him she wants to give Rhea the option to surrender.

Daxamites arrive at CatCo and Winn and Cat are surrounded. Guardian arrives and sprays the aliens with lead dust to weaken them before he knocks all of them out. Cat thanks him, calling him James and tells him she can see his eyes.

Mon-El beams down and calls Alex, telling her Supergirl is still on the ship. The President tells Alex she must destroy the ship and Alex stands there, weighing her options. But while she does that, the cannon blows up.

Kara asks Rhea to surrender. Rhea admits to killing her husband when he disagreed with her and says Kara’s words are wasted. Rhea tells Kara she has lost and a punch sends Kara flying. She looks up and it is her cousin who punched her. Somehow, Superman is under Rhea’s control.

I really enjoyed this episode. I missed Cat and I loved every Cat scene. I like that we finally know the President’s backstory. This was a good episode in giving all the character’s at least one solid scene. The Superman reveal is not my favorite, but I am looking forward to the finale.

Check out the trailer for the season two finale, airing Monday at 8 p.m. on The CW.