Earlier this season they did a "They've been writing fanfic about this for 10 seasons" episode where Clark gets thrust into a universe where Lionel found him instead of the Kents and Clark Luthor is a huge sadistic psycho who killed Lex and is having Luthorcest with adoptive sis Tess. This was the sequel. It's loosely based on the Earth-2 AU in comics-verse, where the Justice League are all criminals.

--Jessica