If there’s a life lesson we can glean from tonight’s very special episode of Supergirl, “Star-Crossed,” it’s a simple one: Whatever you do, don’t lie to your Kryptonian girlfriend. She won’t forgive and she won’t forget. It’s in their/her nature, apparently. Something about how all of that integrity leads to self-righteousness and such. Poor Mon-El (Chris Wood), though. Little did he know that hiding a very minor fact about his background – that he’s the Crown Prince of Daxam, his home planet, presumed lost in the conflagration that destroyed Daxam’s sister planet, Krypton – would lead to the end of his all-too-brief (for him) romance with Kara Zor-El/Supergirl (Melissa Benoist). By episode’s end, Mon-El/Kara romance has been broken asunder and no man, woman (Kryptonian or Daxamite) can change it.
But we’re getting ahead of ourselves. Only an hour later (TV time, not real time), Mon-El and Kara are enjoying some couples time in Kara’s apartment. Mon-El’s suggestion of a musical leads to Kara blurting out her all-time favorite musical (sadly, it’s not Singin’ in the Rain): It’s Funny Face (Audrey Hepburn, Fred Astaire). Before long, though, an alien cruiser has slipped past Earth’s defenses and Daxam’s despotic duo, Rhea (Teri Hatcher) and Lar Grand (Kevin Sorbo), take a page from General Zod’s arrival on Earth in Man of Steel and send out an ABP (All Points Bulletin) seeking the whereabouts of their long-lost son, Mon-El. The revelation matters less to Kara than the now unforgivable fact that Mon-El lied to her. He lied to her when he got to Earth, claiming he was a lowly palace guard saved by the now-dead prince and he lied to her every time he let Kara believe otherwise.
While Mon-El navigates his parents’ arrival and the reason for their galaxy-spanning trip – they want Mon-El to return with them to Daxam and help rebuild their world – Winn (Jeremy Jordan) learns a secret of his own about his alien girlfriend, Lyra (Tamzin Merchant): She’s an alien all right, but she’s a con artist and art thief. She uses Winn’s overactive libido against him, convincing him to break into National City’s art museum, ostensibly for some after-hours, bruise-worthy sexual intercourse, but really so she can steal Vincent Van Gogh’s “Starry Night” for a crime boss/black market art dealer, Mandrax (Paul Lazenby). We later learn than Lyra’s not all bad, though. She might be a liar, con artist, and art thief, but she has a relatively pure motive for the stealing thing: Said crime boss is essentially holding her brother hostage until she makes good on his debt (or something along those lines). For the love-struck Winn, that’s all he needs to break Lyra out of the DEO’s alien holding tank to help her get her brother back.
For Kara and Mon-El, their love story ends on a decidedly downbeat note. Despite a heartfelt plea for forgiveness, Kara can’t bring herself to let Mon-El’s Big Lie go, so she unceremoniously dumps him, crushing his Daxamite heart in the process. Despite the break-up, Mon-El makes a refusal of his own: He rejects his tyrannical parents’ pleas to return to Daxam with them. By episode’s end, they seemingly relent and teleport Mon-El back to Earth where he can play hero again and mope about the DEO’s lux offices. That lasts all of 30 seconds as a new prisoner, the Music Meister (Darren Criss), breaks free of his techno-shackles, steals a dimension-hopping device from a hypnotized Kara, and absconds to the Flash’s universe. Kara drops into Mon-El’s waiting arms, literally lost in a dream where she’s about to go on stage in a ’40s-style get-up and sing her heart out. As they say, “To be continued…” on Tuesday night’s very special crossover Flash episode.