Supergirl had an interesting second season. Not only did the series move to The CW after spending its first season on parent network CBS, but it also delved a lot more into Kara’s life as a person outside of her powers. She fell in love, she got a job as a reporter, and she attempted to get by without the wise words of Cat Grant to guide her.
And she wasn’t the only one experiencing a huge transition, with Alex going through a much-celebrated coming out storyline and James suiting up to become Guardian. With Supergirl’s third season just days away, let’s take a look back at what happened.
In the season premiere, Kara discovers another mysterious alien visitor in the form of Mon-El. While they work to identify him, Kara is distracted by the arrival of Clark – or Superman as he’s better known – and they work together to save the passengers onboard a malfunctioning commercial spacecraft.
The target of the sabotaged craft, they deduce, is none other than Lena Luthor – Lex’s adopted sister and the new CEO of Luthor Corp. Later she is attacked again by assassin John Corben, who announces that he was hired by her brother before being taken out by Lena. At the end of the episode, Project Cadmus – an organisation dedicated to wiping out aliens – are seen reviving Corben as the cyborg Metallo.
Meanwhile, Cat Grant’s open job offer throws Kara for a loop. Working with Clark on the spacecraft case allows her to realise that she wants to become a reporter like her cousin, and she declares this to Cat immediately before her mentor hints at leaving Central City to experience new things.
In terms of her dating life, as Kara and James try in vain to see a date through to the end, she decides that they might be better as friends after all.
Clark sticks around for a while and he and Kara enjoy saving the city as a superhero double-act. That is until they are faced with the Kryptonite-laced Metallo, who was transformed with the help of the substance stolen from the DEO. Alex discovers the mole, who has been working with Cadmus, and J’onn gives the remaining Kryptonite to Clark for safe keeping.
At CatCo, James is left in charge of the company after Cat departs, and Kara runs up against some obstacles with her new boss Snapper. Eventually he agrees to train her as a reporter.
Mon-El wakes up at the DEO and attacks Kara before escaping. Winn, who is now working at the organisation, discovers that he is from Krypton’s neighbouring planet of Daxam and Kara is seen to be increasingly wary of him. It’s eventually revealed that the two planets had a bitter rivalry before their destruction, with both sides believing themselves to be the righteous ones.
President Olivia Marsdin arrives in Central City to sign the alien amnesty act, but her efforts are sabotaged by an unknown alien assailant. Over at L-Corp, Lena tells Kara that the company has developed an alien detection device, which concerns our heroine.
While investigating the attack against the president, Alex meets detective Maggie Sawyer and she reveals the presence of a secret alien bar in town. Later, J’onn discovers that the barmaid there is M’gann M’orzz, who introduces herself as a fellow Green Martian.
Maggie and Alex follow a case to an underground alien fight club. Veronica Sinclair aka Roulette has been kidnapping aliens and forcing them to fight for the entertainment of the rich and powerful. M’gann appears to be a prisoner there, though they soon realise that she fights voluntarily due to her survivor’s guilt. With M’gann’s help, Roulette captures J’onn before Kara manages to save them both.
At the end of the episode, the audience learns that M’gann is actually a White Martian, the Green Martians’ sworn enemies.
The leader of Cadmus is revealed to be Lillian Luthor, and Kara thwarts another of her plans to eradicate earth’s alien threat when extraterrestrial weapons covertly handed to criminals fail to result in the repealing of the amnesty agreement. With the help of Lena, the team destroy the weapons and arrest the criminals, but Cadmus kills them before they can be identified as the benefactor.
Kara takes Mon-El to work with her after he grows tired of the DEO, but he proves himself unsuitable for office life and is promptly fired. In the next episode, it is revealed that Mon-El is using his superpowers to make money, causing Kara to become furious with him.
Meanwhile, Alex and Maggie grow closer and they both acknowledge that there may be something romantic between them. After Alex comes out to Kara, Maggie reveals that she doesn’t want to date someone at such an early stage of self-acceptance. Eventually, the two come together with Maggie declaring that life is short.
Lacking a purpose, James decides to become the vigilante Guardian and eventually recruits Winn as his confidante. They both agree to keep their activities a secret from Kara, Winn reluctantly. When a new vigilante starts killing criminals, they work together to stop him.
An incident with a parasite alien leaves J’onn close to death, and Alex begs M’gann to give blood in order to save him. However, they do not know that she is actually a White Martian and that the blood could have serious unknown side-effects from mixing with his Green Martian blood.
Mon-El is captured by Cadmus, and Lillian demands that Kara come to rescue him. When she gets there, she is taken down by the real Hank Henshaw, who has been transformed by the organisation into Cyborg Superman. With Kara significantly weakened, Lillian is able to take blood samples before Jeremiah Danvers – revealed to be alive – saves both Mon-El and Kara.
Cyborg Superman travels to the Fortress of Solitude asking about the Medusa project. In the following episode, he releases a deadly virus into the alien bar which kills everyone except Mon-El. This virus is revealed to have been created by Kara’s father Zor-El, to protect Krypton from invading aliens.
When Lena gives her mother the isotope she needs to spread Medusa across Central City, it appears she has betrayed Kara. However, when the plan goes through, it’s clear that Lena has ensured the virus is ineffective in order to save the city’s alien population.
When people start to go missing, Kara and Mon-El travel through a portal to Maaldoria, a slave planet that has been taking people from Earth. The planet’s red sun strips them both of their powers, but they manage to overpower Roulette – who is once again behind the kidnappings – and save the prisoners. Upon returning home, Mon-El reveals he wants to become a superhero.
Kara begins training Mon-El, but is disappointed when he opts to save her instead of civilians when out in the field. She is dealt another blow when Guardian’s real identity is revealed and she learns that James has been the vigilante all along.
The group learns that Leslie aka Livewire has been abducted from prison by a scientist draining her powers and giving them to others. In order to prove themselves, James, Winn and Mon-El attempt to rescue her themselves before they are captured and subsequently saved by Kara. She rejects James’ request that they work together, causing a rift between the pair.
J’onn and M’gann ‘bond’ when the latter falls unconscious, and J’onn reveals that he forgives her for the deception. In turn, he learns that she is a traitor and on the run from the rest of the White Martians. Her former mate Armek arrives and, after he is killed, M’gann returns to her home planet.
Lena discovers that she is the product of her father’s affair, and questions her relationship with Lex and Lillian further when she falsely accused of stealing synthetic kryptonite. When she is arrested, Kara is the only person who continues to believe in her.
Mon-El reveals he has developed romantic feelings for Kara and, just as they both confess, the imp from the fifth dimension Mister Mxyzptlk arrives and proposes to Kara. They eventually banish him and decide to give their relationship a go, while Winn begins dating the alien Lyra.
The DEO rescue Jeremiah from Cadmus, but Mon-El is suspicious of him. When he asks Winn to keep an eye on the new arrival, they discover that he is working for Cadmus and has been cybernetically enhanced just like Hank. Before Alex has the chance to confront her father, they realise he has downloaded the list of all registered aliens in America.
Using this list, Lillian begins capturing known aliens in an attempt to deport them to another planet. Kara wants to publish an article about the plan at CatCo magazine but, when she is refused and publishes it on a personal blog instead, Snapper fires her.
Alex convinces Jeremiah to help them stop the launch of the deportation ship.
Daxamites arrive near Earth to retrieve Mon-El, revealing to Kara that her new boyfriend is actually the Prince of Daxam and thus the leader of a people she was raised to hate. After they overcome Mon-El’s dishonesty (with the help of the Music Meister), they must face off with his family as they attempt to take Kara out of the equation.
In order to protect Kara from his mother, Mon-El agrees to leave Earth if Rhea spares her life. J’onn and Kara rescue him but, after murdering her husband for his betrayal, it’s clear that Rhea will not give up easily.
Winn and Lyra’s relationship also hits a rough patch when Lyra sets Winn up for an art museum robbery, leading to his arrest. He later discovers that she did so in order to pay off her brother’s debt, and so forgives her. She later begins working with Winn and James.
Kara is rehired at CatCo after she breaks a story about destructive nanobot technology invented by Jack Spheer, Lena’s ex-boyfriend.
Alex is kidnapped by a childhood friend of the Danvers, and Kara and Maggie must put aside their differences in order to rescue her. By the end of the episode, they have both accepted that they love Alex equally, just in different ways.
When James realises that Guardian is failing to deliver hope to the city in the same way Supergirl does, he begins to doubt his mission. However, a young alien child who only trusts James convinces him that he can do good in his own way.
Rhea has recruited Lena and convinced her to help create the matter transporter, leading to a huge number of Daxamite ships flying over Earth in the hope of conquering the human race. After requesting that Rhea withdraw, a returning Cat Grant and President Marsdin are attacked by the Daxamites. In the process of rescuing them, Kara discovers that Marsdin has been an alien all along.
A full invasion is launched, and Kara resorts to asking Lillian and Cadmus for a way to enter Rhea’s ship and save Mon-El and Lena. Meanwhile, Cat and Winn rally the troops on the ground, M’gann returns with fellow traitor White Martians, and the Luthors develop a lead dispersing device, which would be deadly to all Daxamites including Mon-El.
Once Kara reaches the ship, Rhea reveals that she is in control of Superman via Silver Kryptonite, and he attacks her thinking Kara is General Zod. After overpowering him and taking him to the Fortress, Kara challenges Rhea to a duel between leaders, which she accepts. After revealing that she will not concede even upon losing, Kara orders Lena to launch the device.
At the end of the season, Kara sends Mon-El away from Earth before he is affected by the lead disperser, Cat returns to her position at CatCo and Alex asks Maggie to marry her. A flashback to a pre-destruction Krypton shows the evacuation of another child.
Supergirl season 3 will arrive on The CW on October the 9th and on Sky One in the UK on October the 16th.