Former chief psychiatrist of Arkham Asylum and current inmate Hugo Strange has infected all of Gotham City with a zombie virus that, after 48 hours, will become irreversible. However, just to be sporting, Strange tips of Batman and Robin, giving them a chance to synthesize more of the drug and distribute it before Gotham is well and truly destroyed.
Tropes in this episode include:
- Adult Fear: Robin has a breakdown in the batcave when he realizes that he and Batman are completely alone in Gotham. Batman himself gets a dose when Robin, his surrogate son, is taken and turned.Strange: Of course, with all those zombies running around, I wouldn't feel comfortable going into that neighberhood . . . alone.
- Carrying the Antidote: Strange happens to be carrying it on his person, but "accidentally" drops and breaks it when handing it to Batman. He also apparently creates way more antidote than is necessary for a single person, and is strangely willing to divulge its location. It turns out that it's a mind-altering toxin, and breaking it exposes Batman and Robin to it, who in turn try to expose the entire city to it to "cure" them.
- Find the Cure!: The premise of the episode.
- Batman and Robin are attacked by zombies almost as soon as Strange breaks the antidote. The antidote is actually the toxin, and Batman and Robin were exposed to the fumes.
- Batman is unable to find any trace of the toxin in the air shortly after its "release," which he chalks up to it dissipating quickly. Nor can he find any in the hair follicles of its victims. Of course, this is because Strange didn't actually release anything.
- The zombies yell at him about "poison" and attempt to spray him with something, despite Strange claiming that the zombies spread the virus via biting. Batman is the one who's been poisoned, and they're trying to spray him with antidote.
- When Batman visits Strange again, he's in a different room despite nobody actually being left to unlock his cell door. The police found out what he did and moved him to a higher-security cell.
- Strange claims that he'll only divulge the location of more antidote if Batman takes off his mask, but gives in rather quickly and tells him anyways. He's the one in a hurry, because he needs Batman to spread the drug before it wears off on him.
- Might as Well Not Be in Prison at All: Strange somehow creates a zombie virus and releases it all across Gotham while confined in Arkham. Averted: He has no way of actually releasing it anywhere but directly in or around his cell, and has to manipulate Batman into helping him to spread it further.
- Near-Villain Victory: Batman is literally seconds away from spreading Strange's toxin to everyone in Gotham before he realizes how suspicious the entire setup is.
- Omnidisciplinary Scientist: This episode cemented Strange's role as this, in contrast to the Psycho Psychologist he was earlier in the show.
- Orcus on His Throne: Strange himself never takes an active role in the events after initially releasing the toxin. The room Batman finds him in even resembles a throne room.
- Our Zombies Are Different: This being The Batman, they're kung-fu zombies who can jump ten feet into the air and hold their own against Batman.
- Placebo Effect: Sort of. The toxin apparently requires the victim to believe that there are zombies, at least to some extent. Batman still sees Strange and Robin as normal humans because the former drank the antidote and the latter was wearing a gas mask during the "release." He begins seeing flashes of the "zombies" as humans when he starts to doubt Strange's version of events.
- Suspiciously Similar Substitute: The episode was originally going to feature Scarecrow as the villain, until the writers were told he was still off-limits because of his appearance in Batman Begins, so they rewrote the story with Hugo Strange instead. Tropes Are Not Bad as the change is generally looked upon positively, as Scarecrow's involvement likely would have made the twist more obvious.
- Twist Ending: Rather unusually for this show (which is why it works so well). The "antidote" Strange exposes Batman and Robin to is a toxin that makes them hallucinate that they're in a zombie apocalypse, in order to get them to spread the toxin to all of Gotham.
- Zombie Apocalypse: Strange causes one, Or so Batman thinks.