Official synopsis: THOMAS LENNON RETURNS AS MR. MXYZPTLK – Supergirl (Melissa Benoist) and team must stop Nyxly (Peta Sergeant) from vanquishing a familiar face from Supergirl’s past – Mr. Mxyzptlk (guest star Thomas Lennon). Mxy returns and explains Nyxly’s dark history to the super team in the best way he knows how – in song form. Meanwhile, Lena (Katie McGrath) visits her mother’s birthplace in Ireland, eager to dig into her past but is shocked by the small town’s icy reception towards her. The episode was directed by Glen Winter with story by Rob Wright and teleplay by Elle Lipson & Chandler Smidt (#611). Original airdate 9/14/2021. It seems that Thomas Lennon will be singing, dare I hope that Melissa does too. And now there’s a sneak peak which looks to be directly following the final scene of the last episode.