- "Jerome is dead. Long live me."
- —Jeremiah Valeska
Chaos erupts at the GCPD, sending Gordon on a wild goose chase for the culprit behind the mass takeover. Meanwhile, a friend of Bruce's becomes paranoid, resulting in rash and destructive behavior.
Following posthumous orders from Jerome Valeska, his followers dig up his grave and take it to the Gotham City Police Department to stage a wake. They take over the GCPD after Jim Gordon orders the police to retreat, then surround the building to contain the threat. Edward Nygma infiltrates the GCPD during the chaos to rescue Lee Thompkins, who was left behind in the evacuation. Oswald Cobblepot and Solomon Grundy capture and torture one of Jerome's acolytes to find out who is really directing them in an effort to regain their power.
Jeremiah Valeska hosts Bruce Wayne in his bunker as he demonstrates the self-sustaining energy generator. While talking, Jeremiah reveals that he is struggling against encroaching insanity as a result of Jerome's laughing gas toxin. Jeremiah believes that Jerome is still alive, leading Bruce to take him to Jerome's grave where they find it dug up.
Gordon heads to Jeremiah's bunker, where he is held at gunpoint by Mummer and forced to watch a video where Jeremiah reveals the extent of his involvement in the days events. Jeremiah has modified the energy generator into a bomb, and Gordon barely manages to escape before it explodes.
Jeremiah soon reveals his true colors to Bruce, leading to confrontation between them. Leaving Bruce unconscious, Jeremiah steals more of the self-sustaining energy generators from Wayne Enterprises.
- This episode takes place the morning after the end of "A Dark Knight: To Our Deaths and Beyond", as Lee was just taken into custody the night before "That Old Corpse" begins.
- Jeremiah Valeska applying make-up and dyeing his hair in order to hide his transformation is a direct callback to the 1989 live-action movie Batman, where the Joker did the same to give himself a more normal-looking skin tone and hair color resembling his original appearance. Like Jeremiah, he later also revealed his white bleached skin by wiping off the make-up with a cloth.
- Ecco is as a tribute and predecessor to Harley Quinn, since she also wears a jester costume with a red and black diamond design and acts as the Joker's henchwoman.
- She also acts as a tribute to Alicia Hunt from the 1989 film Batman, who was a blonde henchwoman to the Joker and wore a porcelain mask on missions, similar to Ecco.
- The porcelain mask worn by Alicia Hunt and Ecco is based on a mask worn by the disfigured character Christiane from the 1960 horror movie Eyes Without a Face.
- Jerome Valeska has his last physical appearance on the show, though only as a corpse.