The episode opens with Kara enjoying her "funemployment" by binging Netflix with Mon-El on her couch. They share a kiss just before every television begins playing an alien recording....demanding the release of Mon-El before dawn!
Back at the DEO, Mon-El claims he doesn't know why there's a ship floating above National City looking for him. J'onn looks for Winn, but he's busy breaking into the National City Art Museum to have sex with his girlfriend.
The next morning, Supergirl flies into the atmosphere to confront the alien ship. The alien ship fires a warning shot before enclosing her inside a bubble of some kind. The aliens train all their weapons on Supergirl, but Mon-El intervenes by saying he'll turn himself in. Supergirl returns to the DEO just before Mon-El is set to beam up to the alien ship. Mon-El wants to go alone, but Supergirl grabs Mon-El just as he gets beamed up. When they teleport onto the spaceship, a bunch of aliens start bowing....as Mon-El's parents walk in.
Mon-El thought his parents were dead, and Lar Gand (Mon-El's father) apologizes for attacking Supergirl. Mon-El reveals that he's a prince and that his parents are the rulers of Daxam.
Back at the DEO, Maggie calls Winn about his museum break-in. It turns out that there's a missing painting and the security footage doesn't show Lyra in the museum at all. Winn wants his phone call.
At the most awkward family dinner ever, Mon-El's parents defend slavery (as Mon-El and Kara busted up that slave ring a few weeks ago) before demanding that Mon-El return to Daxam with them. Mon-El also reveals that his guard killed a Kryptonian and stole his ship so Mon-El could escape. Supergirl storms off back to Earth and tells Mon-El she can't even look at him.
Alex and James show up at the police station and convince Maggie to give them 24 hours to clear Winn. When they get back to the DEO, Winn finds out that as a Valerian, his girlfriend Lyra can't be photographed. He also finds out that Lyra has allegedly done this to two other people.
As Winn, James, and Alex begin their search for Lyra, Alex tells Kara to talk to Mon-El and give him a chance to explain himself. Immediately after, Mon-El's mother Rhea beams into the DEO and demands to talk to Kara.
In exchange for Hamilton tickets, Alex gets Lyra's location off of one of the alien bar's customers.
Rhea asks Kara to convince Mon-El to return to Daxam with them. Lyra also points out (rather correctly) that Supergirl is beginning to despise Mon-El because he's Daxamite royalty.
Winn shows up at Lyra's trailer and demands answers. Lyra claims that Winn was just a mark and part of a "long con." When Winn leaves, Guardian arrives to bring Lyra in...but Lyra has backup too. When Guardian and Alex start to get the upper hand on Lyra's "help," they run away and leave Lyra behind with the painting.
Lyra admits in DEO custody that her brother had gotten caught up in an alien gang and that she agreed to help them in exchange for clearing his debt. Winn gets the name of the gang's fence: an ex-Fort Roz prisoner named Mandrax. Winn wants to turn over the painting to Mandrax and rescue Lyra's brother, but J'onn says they can't trust her and urges caution. So, Winn breaks Lyra out of the DEO instead.
Mon-El tries to apologize to Kara, but she says he can't undo his lies. She also tells him not to waste his second chance now that he's discovered that his people and his parents are still alive.
Winn and Lyra try to sell the painting to Mandrix, but Mandrix quickly realizes its a fake. Luckily, Winn brought Guardian along as backup. When Mandrix eventually gets the upper hand on Guardian, Alex and the DEO bust in through the ceiling and arrest everyone. Winn admits to Lyra that his plan was to have the DEO arrest Mandrix and Lyra's gang all along.
Winn returns the original painting and asks Maggie to let Lyra and her brother off the hook. He then convinces Lyra to stay in National City, even though she lied to him. Winn then gives Kara some unsolicited advice about giving Mon-El a chance to explain himself.
Kara comes back to her apartment to find Mon-El waiting for her. Mon-El says that he's a "former prince" of Daxam and that he was inspired by Kara to become a better person. He then tells Kara that he loves her, but Kara can't get over that he lied to her. Kara asks if Mon-El ever planned on telling the truth, but Mon-El can't say that he would have for certain. So Kara ends things with Mon-El, although she doesn't seem too happy about that.
Mon-El returns to the Daxamite ship and tells off his parents. He says that thinking about how he acted on Daxam made him sick. He then demands that his parents send him back to Earth.
The next day, Winn gives Supergirl her interdimensional transporter when Music Miester walks in as a prisoner of the DEO. It turns out the Music Miester was looking for Supergirl. He hypnotizes Supergirl and then uses her transporter to head to Earth-1 to capture the Flash. The episode ends with Supergirl in a dream where she's forced to perform as the opening act in a fancy 1920's club.