|01 "A Dark Knight: Pax Penguina"||09 "A Dark Knight: Let Them Eat Pie"||17 "A Dark Knight: Mandatory Brunch Meeting"|
|02 "A Dark Knight: The Fear Reaper"||10 "A Dark Knight: Things That Go Boom"||18 "A Dark Knight: That's Entertainment"|
|03 "A Dark Knight: They Who Hide Behind Masks"||11 "A Dark Knight: Queen Takes Knight"||19 "A Dark Knight: To Our Deaths and Beyond"|
|04 "A Dark Knight: The Demon's Head"||12 "A Dark Knight: Pieces of a Broken Mirror"||20 "A Dark Knight: That Old Corpse"|
|05 "A Dark Knight: The Blade's Path"||13 "A Dark Knight: A Beautiful Darkness"||21 "A Dark Knight: One Bad Day"|
|06 "A Dark Knight: Hog Day Afternoon"||14 "A Dark Knight: Reunion"||22 "A Dark Knight: No Man's Land"|
|07 "A Dark Knight: A Day in the Narrows"||15 "A Dark Knight: The Sinking Ship, The Grand Applause"|
|08 "A Dark Knight: Stop Hitting Yourself"||16 "A Dark Knight: One of My Three Soups"|
- "You turned everyone I ever loved against me! My own flesh and blood! I guess it's like what they say: We all can go insane with just one bad day."
- —Jerome Valeska to Jeremiah Valeska
Gordon and Bullock try to stay one step ahead as Jerome and his allies Bridgit Pike, Jervis Tetch, Jonathan Crane, and Victor Fries zero in on his next target in the form of Xander Wilde. Meanwhile, Nygma hosts a riddle game show in the Narrows and faces his toughest challenger in Lee Thompkins, and Penguin goes to see Butch with a proposal.
Lee Thompkins challenges Edward Nygma to his game, the Riddle Factory, and wagers to abolish it if she wins. After she outsmarts Nygma, the two share a kiss. Jerome Valeska assembles the "Legion of Horribles" – Oswald Cobblepot, Jervis Tetch, Jonathan Crane, Bridgit Pike and Victor Fries – and sets out to find Wayne Enterprises associate Xander Wilde. Valeska shoots up a Wayne Enterprises building, but to no avail does he find Wilde, and is forced to escape when Jim Gordon and GCPD arrive. With help from Bruce Wayne, Gordon and Bullock locate Wilde, who reveals that he is Jerome's twin brother, Jeremiah, and also reveals that he has kidnapped Jerome. Mad Hatter and Scarecrow break out Jerome from Jeremiah's custody, but are chased off by Gordon and Bullock. Cobblepot convinces Grundy to be hired muscle for the Legion of Horribles, just as Scarecrow concocts a laughing gas for Jerome to spread across the city.
- Michelle Veintimilla returns to reprise Bridgit Pike following an absence where the character was portrayed by Camila Perez in Season 3 and early Season 4.
- Jerome Valeska paraphrases his own version of the infamous "One bad day" line from The Killing Joke comic when he converses with his brother Jeremiah.
- A subtle nod to his colour scheme in the comics, Jeremiah wears a purple tie amongst his Orange Suit and Blue shirt, hinting at his future transformation into a Joker-ish character.