A sinister van drives towards Gotham, as Gordon and Bullock feel as if there are some omens falling upon Gotham, and whenever the next big crime happens, people are going to be all up in arms, blaming the "signs." But as of right now, Gordon seems more concerned with his ever dwindling supply of cigarette stashes discovered, and gotten rid of, by people who are concerned with his health.
Gordon heads down to the GCPD office to meet with some other officers when the lights go off. Gordon can barely see, but he makes out a figure at the end of the hall, standing in blood, and he knows.
Joker is back.
The rest of the lights go black, as Joker makes his way through the room, attempting to tell a joke or two, but getting interrupted by some hecklers, whose neck he cracks. Gordon eventually draws Joker's attention, trying to save the lives of his other police officers. Joker addresses his old "friend" asking how his daughter is, and revealing all the little things he knows, like that last hidden pack of cigarettes he keeps under his bed. By the time the lights come back on, Joker is gone, with his face, and Batman stands over a scared shitless Gordon.
Back in the Batcave, Bruce and Alfred speak about how this was an inevitability. Damian seems none too impressed with the Joker, believing that he's lost his edge, but Bruce warns his son of the contrary. Both Tim and Dick eventually check in, asking if the rumors or true, and if Bruce has told Babs, which he hasn't, believing it's best for her father to tell her. But, eventually Babs does check in, and is a little angry for not being in the loop, as she's found out on her own anyways.
Alfred picks up a signal that's being broadcast over all TV airwaves. It's of a man, painted up like the Joker, but his arms are not that of his own, as the Joker hides behind him, pretending the man is a puppet, and hitting him so he sticks to the script, proclaiming the mayor dies at midnight, before being shot in the head live.
Voice recognition IDs the man on the TV as Henry Claridge, the son of Joker's first victim. The rest of the "family" offers Bruce their help, but are declined, as Bruce believes this to be between Joker and himself.
The Mayor is on lockdown, as Gordon leaves him in a room with 20 or so cops. He begins to speak with Batman who hides in the vents, and tells Gordon that Hady's blood, water, and air supply are all clean. Bruce can't help but feel as if something is off. With all of Gordon's questions, all Bruce can answer is "I don't know Jim." Bruce goes over everything in his head, with the victims, the reenacting of the previous crime, something just feels off. Then it hits him, Bruce rushes into the room, and finds all the cops poisoned with Joker toxin, and the Mayor perfectly safe. Bruce takes a sample and Alfred analyzes it to find some key differences, most noticeably the fact that this toxin makes the victims form a frown, rather than smile. There are also three compounds in it that serve no purpose. Chlorine, ethane and aspirin... move the first letters of those words around, and what does that spell?
Batman heads over to Ace Chemicals, where it all started, and finds the Joker waiting for him, dressed up in his old Red Hood costume. Bruce charges Joker, only to be knocked into an empty vat by a comically large hammer. The vat closes, and begins to fill with chemicals, as Joker takes off his hood, but it turns out, instead of Joker, it's Harley, and even she's a bit disturbed.
With tears coming from her eyes, Harley tells Batman that Mr. J isn't he same anymore, and can't even begin to repeat his plan. Bruce begins to run out of time and demands Harley to tell him where the Joker is...
Wayne Manor... There's a scratching at the door, where Alfred finds a two headed lion cub waiting on the doorstep (one of the previously mentioned omens). He hears a voice behind him say "There's my little guy! I've been looking everywhere!" and finds Joker waiting for him, with a hammer held high.
In the back up, set before the ACE Chemicals scene, Harley looks for Joker, who has yet to reveal himself to her, as he tells her to take off her clothes, and put on the costume he has for her. He eventually reveals himself to her, and begins to speak about making her just like him (cutting off her face) and despite Harley being a bit freaked out, she finally agrees to it, as she closes her eyes. But instead of cutting off her face, all Joker does is place the red dome helmet on her, and tells her what she is to do before disappearing.