The fourth season of the American television series Supergirl, which is based on the DC Comics character Kara Zor-El / Supergirl, premiered on The CW on October 14, 2018. The season follows Kara, a reporter and superpowered alien who fights against those who threaten Earth, and the fallout of her use of mysticism and time traveling. It is set in the Arrowverse, sharing continuity with the other television series of the universe. The season is produced by Berlanti Productions, Warner Bros. Television, and DC Entertainment, with Robert Rovner and Jessica Queller serving as showrunners.
The season was ordered in April 2018, and production began that July. Melissa Benoist stars as Kara, with principal cast members Mehcad Brooks, Chyler Leigh, David Harewood, and Katie McGrath also returning from previous seasons, while Jesse Rath was promoted to the principal cast from his recurring status in season three. They are joined by new cast members Sam Witwer, Nicole Maines, and April Parker Jones.
Kara has stayed busy in her heroic duties working with the D.E.O., and as a reporter at CatCo proving she can multitask. Brother and sister Otis & Mercy Graves attack an alien, Dr. Vose, and steal an EMP device from his lab. J'onn believes it to be a hate crime, with the recent rise in anti-alien hatred in the country, although Kara disagrees. The duo plan to attack President Marsdin's summit to mark the anniversary of her amnesty act. Supergirl saves the President and captures Otis, but Mercy escapes. Camera footage of the attack ends up exposing the President's true identity as an alien. Meanwhile Alex and Brainy struggle to communicate with each other at the D.E.O. The Graves are working with a mysterious masked individual who says he is an "agent of liberty" as he stabs Fiona Byrne, an alien telepath that J'onn had met in a support group for other aliens. The duplicate Kara is seen punching through walls in an underground cavern surrounded by Kasnian soldiers.
In the wake of President Marsdin's outing as an alien, a wave of anti-alien sentiment spreads across the country. Marsdin resigns, leaving Vice President Baker to replace her. Mercy hacks L-Corps' image inducers to disable them, in an effort to force aliens out of hiding. When Brainy is outed to a pizzeria, he is rattled by the hatred he faces. J'onn continues to investigate his friend's disappearance and the trail leads him to Agent Liberty, who holds an anti-alien rally. At L-Corp, Mercy and Lena fight, each using an arm piece of Lex's exoskeleton. Mercy is captured by Supergirl and held at the D.E.O. with Otis. Nia, who reveals herself to be transgender, convinces James to write an editorial against anti-alien hatred. Mercy and Otis convince an agent, Jensen, to release them. Using Lena's lead dispersion device, the three send Kryptonite into the atmosphere, which hits Supergirl mid-flight, making her pass out and fall to the ground.
J'onn catches Kara before she crashes to the ground; he brings her to the D.E.O. and the Kryptonite in the atmosphere continues to weaken her. In an effort to keep her safe while a cure is found, Lena outfits Kara in a prototype armor that will help filter the Kryptonite out of her system. In a series of flashbacks, Ben Lockwood, a university professor, and his family suffer a series of personal tragedies that slowly turn him against aliens and lead him into the path of Mercy Graves, who gives him the Agent Liberty armor. Back in the present, Ben prevents Mercy and Otis from killing Jensen by blackmailing the young agent into breaking them into D.E.O. headquarters.
With the air still Kryptonite-saturated, Kara is not permitted to leave the D.E.O. and fight as it may damage the suit and kill her. Lena and Brainy devise a method to filter the Kryptonite out of the atmosphere. A second D.E.O. agent turns rogue and breaks two aliens out. Mercy kills him after he brings the aliens to her. J'onn meets Manchester Black, Fiona's fiance. Ben hypnotizes the aliens, using Fiona's telekinetic powers, into committing chaos, to give justification for killing aliens. As they attack a carnival, Supergirl fights until her suit is damaged. J'onn and Manchester join the fight and find Fiona, forcing Jensen to deactivate the alien device, breaking the hypnosis on the aliens. Mercy and Otis corner Alex and Supergirl where Otis threatens to expose Supergirl to the Kryptonite-filled air. One of the aliens kills Mercy and Otis as the air is completely cleared of Kryptonite. J'onn is only able to ease Fiona's pain before she dies. Later, Ben transfers a parasite into Jensen, and Manchester purchases lethal weaponry. President Baker assigns Colonel Lauren Haley to be Alex's commanding officer at the D.E.O.
The parasite enables Jensen to absorb an alien's powers through touch, while also killing them. Jensen uses his powers in public and weakens Supergirl enough to escape. Kara and Nia interview a healer alien, Amadei, to counter the anti-alien rhetoric. Amadei is then attacked and left to die without his healing amulet. J'onn and Kara discover the amulet was stolen for the Children of Liberty, to stop Jensen's new powers from killing him. Colonel Haley obtains uranium to use against Jensen and the D.E.O. sets up a containment dome to limit the blast radius. James and Lena meet Ben Lockwood at a media summit, where James asserts that Guardian does not stand for Ben's anti-alien sentiments. Alex convinces Jensen to remove Amadei's amulet, leading to him becoming brain-dead. James believes that if he understands the anti-alien movement, he can get those people to listen, so he contacts Ben.
Masked citizens calling themselves the Children of Liberty patrol the streets, attacking innocent aliens. Supergirl and Manchester intervene and chase them off. Anti-alien manifestos entitled "Twilight's Last Gleaming" rain down on them. Manchester has Children of Liberty member Petrocelli held captive to torture him for information. Haley reprimands Supergirl for intervening in the attack and refuses to use D.E.O. resources to investigate the manifesto. Lena and Eve are frustrated that their experimental trials with the Harun-El rock are not successful. Kara replaces James on a television show where she ends up debating Ben Lockwood, who gets the best of her. James meets Tom, a Children of Liberty member, and they patrol neighborhoods with a dog that can detect aliens hiding. Then the group starts putting together the clues: the alien-sensing dog allowed the Children of Liberty to identify alien houses, and the special lenses that Manchester discovered in Petrocelli's mask will allow the Children to see the infrared marks. At CatCo, Nia's narcolepsy alarms Kara and James. Brainy removes the infrared marks and defeats a group of Children and Kara saves an alien family from Children.
Supergirl is lured by Manchester to Shelley Island, an alien immigration center and monument site where their powers are dampened, where the Children of Liberty detain her and lock her inside the monument and set it to detonate. Manchester previously made a deal with the Children to meet Agent Liberty, but the one he meets is not Ben. James investigates the area, and is almost convinced by the Children to detonate the monument. Kara, whose powers are only partially drained, manages to attract his attention with her heat vision. Manchester, realizing the Children were playing him, destroys the power dampeners, allowing her to escape while Manchester and James fight off the Children. Meanwhile, Lena proceeds with her experiments to enhance humans in an effort to "level the playing field" between humanity and super-beings. She takes on a volunteer, Adam, who dies during the trial, after bonding with Lena through their shared motivational grief. James, unaware of the experiments, goes to make up with Lena. Kara, Alex and Brainy are visited by J'onn who is upset about not being able to stop Manchester from killing people.
Nia wakes up suddenly from a dream involving Agent Liberty. Kara and J'onn look through Manchester's apartment. Kara and Brainy help Nia with her dreams which lead to the old Lockwood Factory where they confront Ben who was confronted by Manchester Black who threatened to kill his wife. Kara stops Manchester Black from killing Ben's wife and sends Ben and Manchester to prison where the latter is visited by J'onn. Later, President Baker demands Supergirl to reveal her secret identity to the world. She refuses, so Baker fires her from the D.E.O.
Barry Allen and Oliver Queen wake up as wanted criminals hunted by John Deegan as a black suited Superman while Kara is imprisoned at S.T.A.R. Labs, with a rewritten Alex guarding her. After narrowly escaping Deegan, Barry and Oliver locate Cisco Ramon, who works as a mob boss with James as a henchman, and retrieve Superman from Earth-38. Supergirl convinces Alex to release her, and together with Barry retrieves the Book of Destiny. Superman uses the book to return Barry and Oliver to their original forms, but Deegan steals it back. Barry and Kara travel in opposite directions to slow the Earth's rotation in order to impede Deegan, despite Clark saying it will kill them. With help from Lois, Brainy, and J'onn, Superman and Oliver successfully defeat Deegan and restore Earth-1 to normal. On Earth-38, Clark reveals Lois is pregnant, and they are going to be moving to Argo City for a while, leaving Earth in Kara's hands. Clark proposes to Lois and she accepts. On Earth-1, Oliver gets a call from Batwoman, revealing Deegan is in Arkham and has seemingly made friends with the Psycho-Pirate.
This episode concludes a crossover event that begins on The Flash season 5 episode 9, and continues on Arrow season 7 episode 9.
Colonel Haley dismisses Kara from a crime scene because of Supergirl's continued refusal to reveal her identity. All the D.E.O. agents who know Supergirl's identity, including Alex, agree to resist Haley's interrogations. Kara, Alex and J'onn learn that the attackers were Morai, a trio of aliens with the ability to turn invisible, but Kara can slightly see them, which she describes as a "shimmer." One Morai kills itself to avoid Haley, who trained them to be weapons using intimidation tactics. Two more Morai infiltrate the D.E.O., and Brainy marks them with a paintball gun so the agents can see them. Haley re-enables the use of lethal weaponry, killing one of the Morai. Haley and Alex are saved by Supergirl from the last Morai. Haley realizes that Supergirl is Kara, and tries to blackmail her back into the D.E.O. before Alex incapacitates her. J'onn wipes Haley's mind of Supergirl's identity, but Haley remains determined to discover it, going as far as to bring in an alien truth-seeking creature to ferret out the secret. To keep Kara's identity safe, Alex has J'onn wipe everyone's memory of Supergirl's identity including her own.
While training, the Supergirl copy suddenly gets a nosebleed and falls into a coma. The Russians try to shock her back, but when they do it at full power, it sends purple lightning around the globe that causes drugs to begin glowing and turn purple. If someone takes the purple drugs, they transform into a Hulk-like monster that drives them mad. This catches the D.E.O.'s attention. The group continue their lives, but Kara feels a mild disconnect with Alex due to her no longer remembering that Kara is Supergirl. Alex attempts to sort things out, but seems to feel that part of her memory is missing, asking J'onn to take a look. J'onn and Brainy agree to try placing a placebo in Alex's mind to cover the truth about Supergirl. Meanwhile, Kara comforts Nia when she has a crisis of confidence about her family when she discovers she has developed the Dreamer powers that occur in her family to one female in every generation, as Nia did not want them. Nia's sister renounces her when she discovers Nia has the powers, since she was expecting to get them, due to Nia being transgender. Kara reveals her identity to Nia to reassure her that she understands and that Nia is not alone. Nia talks to her mother about her abilities, and her mother comforts her, before dying of a spider bite. Alex ends up confronting Supergirl and appears hostile towards her, still having no memory of Supergirl's true identity.
After a meteor crash lands, Pamela Ferrer, a thief, and her boyfriend are caught in a car crash. A symbiotic, snake-like alien parasite known as Menagerie inhabits Pamela's body. Meanwhile, Brainy requests Nia to train with him but refuses as she is still grieving her mother, although she decides to invite Brainy to a Valentine's Day party. Alex decides to give advice for Brainy. Ben Lockwood convinces his son to lead the Children of Liberty. After, the D.E.O. track down Pamela who attacks the Valentine's Day party. Following a confrontation with Kara, Nia and the Children of Liberty, the parasite is (apparently) killed. Pamela is arrested and put in prison where she gets a message from Manchester Black. President Baker realizes crimes are only considered terrorist attacks if they are against humans, not aliens, forcing him to release Ben from prison. It is revealed that the symbiote is still alive.
Manchester breaks out of prison with Hat and Menagerie who together form "The Elite," along with a Morai. Hat is revealed to be an alien whose Bowler hat has fifth-dimension properties. Meanwhile, Brainy trains Nia at the Fortress of Solitude. Supergirl confronts President Baker to convince him to prevent a missile launch carrying a satellite which would destroy any alien ship coming to Earth, but he refuses. Later, Supergirl, Nia, Brainy, Alex, and J'onn stop The Elite, while Supergirl learns that the satellite has been reprogrammed to destroy The White House. She redirects the satellite so that it fires at a body of water and then destroys it. However, Manchester manages to flee with the Legion ring he stole from Brainy during their confrontation. Ben is offered to be Director of Alien Affairs by the President. At the same time, Alex begins distrusting Baker after Haley confirms that the President took action against protocol; to this end, she offers Lena anything she needs for her research.
Ben starts a revolution against aliens which gets The Elite's attention and they decide to help the aliens resist against the humans. However the revolution eventually fails when aliens and humans begin to bond. Supergirl, Nia and J'onn defeat the Morai, The Hat and Menagerie. J'onn fails to stop Manchester so he decides to begin a manhunt. At Cat Co, James gets shot by an unknown figure.
Four years ago, Lena's brother Lex created a red sky over Metropolis to take down Superman but was caught and sent to prison. In the present, Lex is freed from prison due to a disease and Lena decides to help Lex by working on a cure. Meanwhile, J'onn and Kara continue investigating Manchester who confronts the two by using the Martian Staff of Kolar which triggers J'onn's traumatic memories to come back. Later, Lena decides to use the cure on James and his sister Kelly tries to stop her but Alex convinces Kelly to let Lena use the cure to save the momentarily-dead James. However just before they use the cure, Manchester causes a power outage across the city so Kara and J'onn confront Manchester again. J'onn kills Manchester while Kara stops the city from being flooded. The following day, Lena exposes that Lex cut off the backup power and he also admits that Otis (thought dead) shot James on Lex's orders all so that Lena would have no choice but to test the cure on him. It is also revealed that Eve was working with Lex and Otis this whole time. Otis chloroforms Lena leaving Eve to look after her. Lex escapes with Otis but is stopped by Supergirl.
Three years ago, Lex was put on trial for mass murder but before going to prison he is visited by Eve (revealed to be a fangirl of Lex), who is hired by Lex to go undercover to spy on James. Nine months ago, the Kasnians found a stray, amnesiac copy of Supergirl, who was created from Black Kryptonite, and informed Lex about this four months later. Since then, the Kasnians have been training the Supergirl copy while Lex raised and manipulated her for his own uses, teaching her a biased history about her rival, the original Supergirl. It is also revealed that Lex planned for Lena to test the cure in order to save the Supergirl copy from a sudden illness that rendered her comatose due to her being created from Harun-El. Lex gives the cure to the Supergirl copy whom he names Red Daughter. In the present, Lex is revealed to possess metahuman powers, which he uses to escape from Supergirl.
Supergirl teams up with Alex and Lena to track down Eve, who is the only weak link of Lex's they can exploit. They track down her cousin Bitsie, whom they learn was given the cure to eradicate her cancer; persuaded to help, Bitsie reveals the location of Eve's old lab. It is revealed that Eve shot James and used the Kryptonite heart used for Metallo to resurrect Otis. Supergirl finds Black Kryptonite in the vault, with Lena explaining she created it and its been the basis of her medical research; Supergirl reveals that her "seeing red" about such things is because she's constantly worried about people like Lex gaining powers and her not being able to stop them. J'onn also leaves the planet after seeing a vision of his father. During a press conference at the White House, in which the Alien Amnesty Act is officially repealed, Red Daughter attacks disguised as Supergirl to turn public opinion against her. President Baker declares martial law against Supergirl, who is now public enemy number one, though Alex, Lena and Haley all believe she is innocent. Having been attending, James is left unable to move out of fear, so he turns to his sister for therapy.
Alexis Ostrander and Jesse Warn will direct the remaining episodes of the season.
At the Television Critics Association press tour in January 2018, The CW president Mark Pedowitz said he was "optimistic" and "confident" about Supergirl and the other Arrowverse shows returning next season, but added that it was too soon to announce anything just yet. On April 2, The CW renewed the series for its fourth season. Robert Rovner and Jessica Queller returned to serve as the season's showrunners without their former co-showrunner Andrew Kreisberg, who was fired during the previous season.
Following the conclusion of the third season, which closed with a second Kara Danvers born from the aura that escaped during the final battle with Reign being found by Russian soldiers in Siberia, Robert Rovner and Jessica Queller confirmed that the fourth season would be inspired by the Superman: Red Son comic book mini-series. Queller described the adaptation as "an homage" to the series, which portrays what would have happened if Superman had landed in Russia and became a hero there instead of in America. The story intends to examine the nature-versus-nurture debate, and will develop as a "slow-burn" throughout the season.
At San Diego Comic-Con 2018, Rovner and Queller stated that the season would aim to be more "grounded" than previous seasons in order to touch on topical real-world issues. They confirmed that the fourth season would look to refocus on Kara's professional career as a reporter and see her act as a mentor to Cat Grant's former protégé, both at CatCo and as a superhero, paralleling Kara's own journey of coming into her own. The duo added that "This is the season where Kara becomes as much a hero as Supergirl." Teasing the main villain of the season, the producers described Agent Liberty as the leader of "a hate group that supports a human-first world order" and, under the guise of a family man, provokes "anti-alien sentiment in the country, echoing the hateful rhetoric we're seeing right now in certain American politics."
Rovner and Queller also announced that the theme of the season would be "What is stronger: hope or fear?" Melissa Benoist commented that, "I think their main premise is that fear itself is a villain, and can hope conquer it? Supergirl stands for hope, so we'll see." Queller concurred, adding that the season would investigate, "How can [Supergirl] be a beacon of hope when she represents what people are afraid of?"
Main cast members Melissa Benoist, Mehcad Brooks, Chyler Leigh, David Harewood, and Katie McGrath return from previous seasons as Kara Danvers / Kara Zor-El / Supergirl, James Olsen / Guardian, Alex Danvers, J'onn J'onzz / Martian Manhunter, and Lena Luthor, respectively. The fourth season is the first not to feature original cast member Jeremy Jordan, who plays Winn Schott. While it was initially announced that he would shift into a recurring capacity for the fourth season, Rovner later said he would not appear until the fifth season. Chris Wood and Odette Annable, who became regulars in the second and third seasons, respectively, will not reprise their roles as Mon-El and Samantha Arias / Reign, respectively, as regulars in the fourth season. On June 15, 2018, it was announced that Jesse Rath was promoted to a series regular after previously recurring in the third season as Querl "Brainy" Dox / Brainiac 5. On July 17, it was reported that Sam Witwer had joined the main cast as Agent Liberty. On July 21 at San Diego Comic-Con, it was announced that Nicole Maines and April Parker Jones had been cast as series regulars and would portray Nia Nal / Dreamer and Colonel Lauren Haley, respectively, with the former to become the first transgender superhero on television.
Brent Spiner was originally cast as Vice President Baker in August, but the role was recast later that month with Bruce Boxleitner due to Spiner having "family issues conflicting with the show's production dates." In October, it was announced that the character Lex Luthor, Lena's half-brother and the archnemesis of Kara's cousin Superman, would be introduced this season. The following month, Jon Cryer, who portrayed Lex's nephew Lenny Luthor in the film Superman IV: The Quest for Peace, was cast in the role.
Production for the season began on July 11, 2018, in Vancouver, British Columbia, and was set to conclude on April 15, 2019. Melissa Benoist joined filming following the conclusion of her run on Broadway as the star of Beautiful: The Carole King Musical on August 4, 2018.
In May 2018, Arrow star Stephen Amell announced at The CW upfronts that the next Arrowverse crossover would feature Batwoman and Gotham City. The crossover "Elseworlds" is slated to launch a 2019 solo series for the character.
In May 2018, it was announced that Supergirl, which had aired on Mondays since its debut, would move to Sundays for its fourth season due to The CW's programming expansion to Sunday nights. The season premiered on The CW in the United States on October 14, 2018. The annual crossover episode will swap time-slots with The Flash for that week and will air on Tuesday, December 11.
The main cast of the season as well as executive producers Robert Rovner, Jessica Queller, and Sarah Schechter attended San Diego Comic-Con on July 21, 2018 to promote the season.
The review aggregation website Rotten Tomatoes reports a 90% approval rating for the fourth season, with an average rating of 7.22/10 based on 87 reviews. The website's critic consensus reads: "Though it's a little tonally inconsistent, Supergirl's fourth season still soars thanks to strong, relevant writing brought to life by its charming cast."
Reviewing for Den of Geek, Delia Harrington gave the premiere a rating of 4/5, writing: "The Supergirl season 4 opener sows the seeds of a season's worth of conflict while being a great episode in its own right." IGN's Jesse Schedeen said of the premiere that, "After a disappointing finish to a generally underwhelming Season 3, it's good to see Supergirl quickly bouncing back this week. 'American Alien' sets the stage for a promising conflict to come, introducing memorable new villains and supporting characters and forcing Kara to confront the things she can't control in her city. Supergirl is borrowing several pages from the X-Men playbook, and that's by no means a bad thing." He gave the episode a rating of 8.6/10, concluding that, "Supergirl's fourth season is off to a promising start thanks to an eventful and dramatic premiere episode." Caroline Siede of The A.V. Club concurred with Schedeen's X-Men comparison, reflecting that over the seasons, "[Supergirl] has grown both more explicit and more nuanced in its handling of social and political issues." Siede gave the premiere a "B+" grade, explaining, "I'm tempering my optimism with just a little bit of caution. [...] Supergirl still has plenty of room to grow, but it's nice to see the show get its core ethos so right."
^ Credited on-screen as "Brian Cybert".
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