Warning: The following recap contains major spoilers for Supergirl episode 19, Alex.
The episode opens with Maggie attempting to resolve a hostage situation. Supergirl flies in to apprehend the robbers, upsetting Maggie. Her feelings are revealed when they meet for dinner plans with Mon-El and Alex. Kara and Maggie passive aggressively argue over the consequences of Supergirl’s actions and how criminals use her actions as a defense to have their charges dropped. Kara scoffs at the idea of her actions being more detrimental to human criminals while Maggie defends her belief that Supergirl’s involvement in human criminal activity sometimes results negatively. Kara leaves the room, Mon-El chasing after her, and Alex leaves to talk to her as well.
Lena meets with Rhea and praises her proposal of a trans-matter portal, and Rhea says she needs Lena in order to make the portal function completely.
Kara is visited by Maggie at work, who is searching for Alex. They both conclude that Alex has not checked in with either of them or the DEO. Kara receives a call and is told that Alex is being held captive and will die unless Kara frees a man named Peter Thompson. The caller also reveals that they know Kara is Supergirl.
Alex wakes up in a cell, claiming she knows her kidnapper.
The DEO team is then seen discussing how to find Alex without negotiating with terrorists. After reaching multiple dead-ends, they realize they must understand who Peter Thompson is.
Lena and Rhea are seen drinking together, and Rhea gives Lena the remaining details of her trans-matter portal. They toast to being new friends regardless of business matters.
John, Maggie, and Kara visit Peter Thompson in order to interrogate him and discover further details. Kara loses her temper and dents the table. Winn calls to tell Kara that Peter Thompson has a son, Rick, whom Kara went to school with.
Supergirl flies to Rick’s house, where she sees Alex being monitored by security cameras. Rick allows Kara to talk to Alex, however Rick refuses to let her go until his father is freed. Kara threatens to hurt him, but stops when she realizes she needs him to tell her where Alex is.
Kara brings Rick in to be interrogated. He reveals he’s been planning this for a year, as well as how he came to know that Kara was Supergirl. He also reveals his connection to his father and his eagerness to see who loves Alex more, Kara or Maggie. Maggie then determines that his connection to his father makes his father the key to getting Alex back.
Lena and Rhea meet in her office and Lena reveals that she knows Rhea is an alien. She then refuses to help her build anything and kicks her out of her office.
Ricky and his father are reunited at the DEO, until John makes a slight mistake, revealing that he is only posing at Peter Thompson. Ricky then tells them their time is running out.
Alex is seen ripping the tracker in her body from her skin, connecting it to the security camera. Winn receives the location and tells Kara. She tells Maggie and Rick, then reveals that she will fly to rescue Alex. Rick warns her against it, then Maggie tells her not to go due to Rick’s unflinching attitude at the news.
Supergirl leaves regardless, and flies to Alex. When she rips a piece of the floor that she believed was the ceiling of the cell, a timer begins counting down from four hours. Alex’s cell then begins flooding with water.
Supergirl enters Rick’s interrogation room demanding he reveals Alex’s location. He refuses and allows Alex to talk to Maggie and Kara. Maggie and Alex desperately talk to each other until the connection breaks. Maggie and Kara argue over who was right, until Maggie makes it clear that she has as much say over Alex as Kara.
Rhea appears before Lena in order to talk, hoping Lena will reconsider working with her on the portal.
Lena calls Kara and asks for her advice, but Kara says she’ll call her back. John then consoles Kara.
Rick attempts to sway Maggie into freeing his father in exchange for Alex, while Alex is seen attempting to break free of her cell which is quickly flooding.
Maggie is seen at the prison freeing Patrick Thompson, only to be stopped by Supergirl who tries to convince Thompson to stop Rick from killing Alex in order to spare his humanity. Patrick reveals Alex’s location, and Maggie and Supergirl are able to free her in time.
In the end, John prepares to mind-wipe Rick, while Kara and Maggie reconcile their differences. Lena then agrees to work together with Rhea.
This episode was very emotional, however did not forward the overarching plot of the season significantly. The conflict between Kara and Maggie seemed very real, although Rick’s role in the episode was only used forward the plot. The sub-plot regarding Lena and Rhea seems to set up the penultimate conflict of the season.
Supergirl airs Monday nights on The CW, at 8/7 Central.