"Lex and Lena Luthor, teaming up to save Superman's best pal. What would Mother think?"
Lex Luthor to Lena Luthor
"O Brother, Where Art Thou?" is the fifteenth episode of the fourth season of Supergirl, and the eightieth episode overall. It aired on March 17, 2019.


Secretly furloughed from prison due to failing health, Lex Luthor visits his sister, Lena, to seek her help finding a cure. Savvy as ever, Lena is suspicious of Lex's motives but when she's faced with a life and death situation, she must decide how she truly feels about her brother. Meanwhile, Supergirl and J'onn face off against Manchester Black. James' sister Kelly comes to town.[src]


  • The episode's title is a reference to a fictional book of the same name in the 1941 film Sullivan's Travels.
    • The title of this episode is from a Coens Brother 2000 film of the same name about the convicts who record a song in the depression era and become famous. The movie also draws a lot from the epic poem The Odyssey by Homer.
  • In the flashback at the beginning, Lex turned the sun red in a bid to de-power Superman, a reference to The War of the Superman storyline in 2010, when he briefly turned the sun red to save Earth from an invasion of hostile Kryptonians.
  • Lex's act of creating an earthquake is a reference to the original Superman (1978), where Luthor's master plan was to use the quake to sink the west coast and turn the near-worthless desert real estate he'd bought up into a valuable water-front property.
  • Lex having inoperable cancer after injecting himself with Kryptonite is a reference to the original comics, where he discovered that Kryptonite radiation was deadly to humans (if not quite so fast-acting as it is with Kryptonians) after he began wearing a Kryptonite ring to keep Superman at bay and later developed cancer.
  • Brainiac-5's contention that he usually gets along so well with machines may be a reference to his creation, in the DC comics, of COMPUTO, a sentient machine which became one of the greatest adversaries of the Legion of Super-Heroes.
  • While looking at a portrait of Lillian, Lex mentions how her eyes seem to follow one around, the same observation Mrs. Queller makes to Alex in "Shelter from the Storm".
  • It is implied Lena's mother was Irish, another nod to the former's actress, Katie McGrath, being Irish.


  • There's a factual error in Lex's citation. Epicurus lived between 341–270 BC - making his statement over 2000 years old instead of ~280.


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