Aliens attack National City with the intention of collecting a large bounty put out on Supergirl.
Supergirl goes on high alert when a new villain comes to National City. In other events, Winn’s new girlfriend gets him in trouble with the law and the Music Meister attacks.
Alex and Kara realize they must break the rules to foil Cadmus’ latest plot.
When Jeremiah Danvers is rescued from Cadmus, Alex and Kara are thrilled to have him back, but Mon-El is suspicious about his sudden return.
A magical imp called Mr. Mxyzptlk arrives on Earth and wreaks havoc on National City when Kara doesn’t reciprocate his feelings.
Lena is arrested when Metallo breaks Lillian out of prison and evidence suggests that Lena is responsible.
A White Martian called Armek comes to National City with the intention of bringing M’gann back to Mars to be punished for her treason.
When Livewire apparently breaks out of prison, Supergirl sets out to recapture her.
While searching for a missing woman, Supergirl and Mon-El end up on another planet where Roulette leads a slave trafficking ring.
As Eliza comes to National City for Thanksgiving, Kara turns to Lena for help when Cadmus unleashes a virus that instantly kills aliens, then is asked by Barry Allen and Cisco Ramon for help with an alien invasion on their Earth.
Supergirl comes face-to-face with Cyborg Superman when she attempts to save Mon-El from Cadmus.
The Guardian arrives to lend a hand when an alien parasite drains Supergirl of her power. Mon-El contemplates his motives when he considers a new career. Alex faces a new reality.