Original air date: 10/14/2018 Runtime: 42:25 min. Diving back into reporting, Kara welcomes new reporter Nia Nal to CatCo in the season four premiere. Meanwhile, James and Lena argue about his impending indictment for acting as the vigilante, Guardian, while Alex and Brainy struggle to get in sync at the DEO. Then, Supergirl is called into action when remnants of the anti-alien terrorist organization Cadmus try to assassinate pro-alien leaders, but their endgame turns out to be much more sinister than she expected. J’onn relishes his peaceful new life, but an outing with an old friend causes him concern.
Original air date: 10/21/2018 Runtime: 42:20 min. A shocking revelation causes chaos in National City. While Alex takes control at the DEO, Supergirl sets out to capture Mercy Graves (recurring guest star RHONA MITRA). Back at CatCo, Kara decides to write an investigative story on Mercy and asks Lena to introduce her as she has ties to the Luthors. Meanwhile, Brainy meets Nia and the two end up in a precarious situation.
Original air date: 10/28/2018 Runtime: 40:55 min. Ben Lockwood (SAM WITWER) didn’t always hate aliens. Through a series of incidents, and input from his anti-alien father (guest star XANDER BERKELEY), Ben slowly transforms from a mild-mannered professor into the villainous Agent Liberty to today.
Original air date: 11/04/2018 Runtime: 42:14 min. When Supergirl needs help, Alex asks Lena and Brainiac to team up. Meanwhile, J’onn questions his decision to quit the DEO. However, after running into Manchester Black (guest star DAVID AYALA), he realizes there are a lot of ways to help his fellow aliens during this tumultuous time.
Original air date: 11/11/2018 Runtime: 42:23 min. Colonel Haley (new series regular APRIL PARKER JONES) makes a surprising decision regarding Supergirl. Meanwhile, Kara writes a series of articles highlighting aliens in National City in the hopes that humans will stop being so fearful of them. Unfortunately, the articles put some of the aliens in harm’s way.
Original air date: 11/18/2018 Runtime: 42:23 min. Although everyone gathers for Thanksgiving, Kara is feeling down after her televised debate with Ben Lockwood about the anti-alien sentiment coursing through National City. Meanwhile, James and Lena argue about the best way to handle the Children of Liberty.
Original air date: 11/25/2018 Runtime: 42:23 min. James falls in deeper with the Children of Liberty in his efforts to meet Agent Liberty. Meanwhile, Supergirl and Manchester Black follow a lead on Agent Liberty’s location, but things take a dark turn. And Lena kicks off her first set of trials. Chad Lowe directs.
Original air date: 12/02/2018 Runtime: 42:22 min. In the midseason finale, Nia has a powerful dream about Agent Liberty, but refuses to look at it as a prophetic dream and pushes it aside. After noticing something is bothering Nia, Kara enlists Brainy’s help, and the two try to persuade Nia to embrace her destiny. Meanwhile, Manchester Black pays Ben Lockwood a menacing visit. Kevin Smith directs.
Original air date: 01/27/2019 Runtime: 42:20 min. Kara joins Nia on a trip to Nia’s hometown to visit her family during the town’s annual Harvest Festival. While home, Nia’s mother, Isabel (guest star KATE BURTON), encourages her daughter to embrace her destiny. Meanwhile, Alex deals with a dangerous street drug that is turning people violent and giving them temporary superpowers.
Original air date: 02/17/2019 Runtime: 42:25 min. With his P.I. shingle newly hung outside his office, J’onn welcomes new clients. Trying to take her mind off what happened at the DEO, Kara decides to team up with J’onn on his latest assignment, which unfortunately ends up tying directly into Alex’s current investigation that involves the villain Menagerie (guest star JESSICA MERAZ). Meanwhile, Lena shares some news with James, but his reaction isn’t what she expected. Nia invites Brainy to her Valentine’s Day party.
Original air date: 03/03/2019 Runtime: 42:13 min. When Manchester Black breaks out of prison with the help of his new team, The Elite, who are set on punishing the anti-alien forces, Supergirl pulls double duty as she tries to apprehend Manchester Black and his team as well as dealing with a shocking new development with Ben Lockwood.
Original air date: 03/10/2019 Runtime: 42:28 min. Between Ben Lockwood’s new push to stir up the anti-alien movement and the Elite’s desire to target Lockwood and his minions, Supergirl is concerned about the safety of the American people – both human and alien. When Lockwood organizes a rally, the aliens decide to peacefully protest. Brainiac and J’onn join the alien march while Supergirl and Dreamer patrol to keep everyone safe. Meanwhile, James picks up his camera again to cover the march for CatCo, and Haley assigns Alex a job that clashes with her beliefs. When The Elite and Ben Lockwood stir up trouble at the rally, Supergirl is forced to take a stand. JONATHAN BENNETT guest stars.
Original air date: 03/17/2019 Runtime: 42:24 min. Secretly furloughed from prison due to failing health, Lex Luthor (special guest star JON CRYER) visits his sister, Lena, to seek her help finding a cure. Savvy as ever, Lena is suspicious of Lex’s motives but when she’s faced with a life and death situation, she must decide how she truly feels about her brother. Meanwhile, Supergirl and J’onn face off against Manchester Black. James’s sister Kelly (guest star AZIE TESFAI) comes to town.
Original air date: 04/21/2019 Runtime: 42:25 min. Supergirl and Lena head to Stryker’s Island to search for clues on how to defeat Lex. At the prison, Supergirl tries to befriend a nosy prisoner, Steve (guest star WILLIE GARSON), who may have insight into what Lex was doing, but he and all of the prisoners regard her as a traitor to the country and refuse to talk to her. Lena realizes Lex left behind clues for her and deciphering them could be the key to his whereabouts. Meanwhile, Kelly encourages James to talk to someone about his PTSD, and Alex faces off against Ben Lockwood after he storms the DEO and acquires some powerful weapons to hunt Supergirl.
Original air date: 04/28/2019 Runtime: 42:25 min. As Kara doggedly works as a reporter to clear Supergirl’s name, Dreamer picks up the slack as National City’s protector, which leads to a showdown with Ben Lockwood. James takes drastic measures to relieve his PTSD. Series star David Harewood directs.
Original air date: 05/05/2019 Runtime: 42:22 min. Kara and Lena head to Kaznia to hunt down Lex. However, Eve Tessmacher (recurring guest star ANDREA BROOKS) sets a trap for the duo that could ultimately reveal that Kara is Supergirl. Meanwhile, Alex gets a long-awaited phone call, James practices using his powers, and Ben Lockwood takes a dangerous stand inside the DEO.
Original air date: 05/12/2019 Runtime: 42:24 min. Kara 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 turns to an unlikely source for help – Lillian Luthor (guest star BRENDA STRONG). Meanwhile, Alex realizes she’s missing parts of her memory; And Brainy, Nia and J’onn set out to track down aliens who have been abducted by Lex.
Original air date: 05/19/2019 Runtime: 42:19 min. In the fourth season finale, Lex Luthor descends upon Washington, D.C. and summons Lena and Lillian Luthor to the White House. Realizing that she’s got one last chance to stop Lex, Supergirl turns to the power of the press to help her.