When Jeremiah Danvers is rescued from Cadmus, Alex and Kara are thrilled to have their father back. The Danvers arrange a family dinner to celebrate but things go awry when a suspicious Mon-El starts to question Jeremiah about his sudden return.
When Mr. Mxyzptlk, a magical imp, shows up on Earth and declares his love for Kara, she tries to let him down easy, thinking him harmless. However, he decides it’s a challenge and starts to wreak havoc on National City. Mon-El has seen beings like Mr. Mxyzptlk on Daxam and knows how dangerous they can be. He and Kara argue over how to get rid of Mr. Mxyzptlk, further straining their relationship. Meanwhile, Alex and Maggie celebrate their first Valentine’s Day together.
Armek, a White Martian, descends on National City intent on taking M’gann back to Mars to face her punishment as a traitor. Hank and Supergirldetermine the best way to keep M’gann safe is to bring her to the DEO. However, when it is revealed that Armek shape-shifted into M’gann and is now loose in the building, the team realize he could be disguised as any one of them.
After Livewire seemingly breaks out of prison, Supergirl is intent on recapturing her. After training Mon-El, Supergirl takes him with her when she sees Livewire attack the NCPD but things go awry when Mon-El puts Supergirl before the citizens of National City. Meanwhile, James decides to come clean with Kara and M’Gann, has a psychic attack and collapses into a coma.
It’s the biggest and best superhero team-up ever! The epic four night crossover event begins Monday November 28th featuring all-new episodes of The Flash, Arrow, Supergirl, DC’s Legends of Tomorrow.
Supergirl comes face-to-face with Cyborg Superman when she attempts to save Mon-El from Cadmus.
The Guardian debuts to lend a hand after a parasite alien drains Supergirl of her power. Mon-El considers a less than desirable new career which then leads him to contemplate his motives. Alex struggles with a new reality.
Supergirl must beat a ruthless new gang who has been armed with dangerous new alien technology. When Cadmus sends a video to the DEO, the team realizes Cadmus is the one staffing the criminals for a secret mission. Meanwhile, Kara gets Mon-El a job as an intern at CatCo, James makes an important decision and Lena invites Kara to attend one her fundraisers.