Batgirl (voiced by Tara Strong) is a costumed vigilante who assists Batman (Kevin Conroy) when she can, but recently relations have become strained between them, with her mentor telling her she is not up to the job of taking down the worst that Gotham City can throw at her, and a recent altercation with criminals stealing a bank van would appear to bear that out. There had been a chase with the cops and the gangster Francesco (John DiMaggio) had managed to evade them and Batman and Batgirl, though he did not get the loot, but now the young woman was on the bad guy's radar, he started to grow obsessed with her. Batman warns her that this will not turn out well, but she is determined to prove herself...
The Batman Animated Universe had been around since the early nineteen-nineties when it was created (by Bruce Timm, among others, a producer here) to capitalise on Tim Burton's concept of the famed Bob Kane and Bill Finger characters. It had branched out into feature length specials, the first of which, Mask of the Phantasm, had been afforded a theatrical release, though thereafter these were released straight to video, later DVD, Blu-ray and streaming over the internet; they had proven themselves a nice earner for Warner Bros' animation department, especially when they started adapting popular graphic novels from the comics series. The Killing Joke was something different, however.
Writer Alan Moore and artist Brian Bolland were regarded as two of the greatest talents to emerge from eighties comics, and when they teamed up to create this it was big news for the fans. It was a controversial story, as it was one of those graphic novels to bear the message on the cover "Suggested for Mature Readers", meaning this was not for the little kids, and it certainly lived up to that as one of the grimmest tales ever to feature Golden Age characters up to that point, not least because it featured The Joker carrying out a particularly nasty item of point making that saw Batgirl at a severe disadvantage, then her father Commissioner Gordon (Ray Wise) about to follow suit if the twisted villain had his way.
Seeing as how the Batman cartoon features had been kiddie-friendly up to that stage, crafting a version of that, which contained a Joker origin story to boot, then The Killing Joke was a gamble, but buoyed with the success (financial, if not critical) of the live action Batman v Superman: Dawn of Justice DC gave it all the fanfare they could, offering it a limited cinematic release in the process. However, it was not the Moore material (as usual, his name was left off the credits at his own request) that was the trouble, it was the fact that the half hour padding that out to feature length was not up to snuff, and held a scene that many fans were deeply unhappy with: Batman and Batgirl having sex with each other! They saw their relationship as one of mentor and pupil, so anything sexual between them was a no-no.
Perhaps it was interesting that while many of those fans were content to accept the theory that The Joker raped Barbara after his initial attack, something denied by Moore, the idea that she would be having consensual sex with Bruce Wayne was a step too far, but really the main issue was that they had to include that made-up opening act at all. The Killing Joke had been all about Batman's symbiotic connection to his arch-enemy, and although Batgirl was vital to the story, she remained in the victim role, an impetus for the Dark Knight to finally confront the weird need he and The Joker had for each other that was only going to conclude with one of them dead. Yet mostly, this confirmed that some things are comic books for a reason, as the animation and voice acting failed to bring what on the page was absorbing if unpalatable in its way, to life; Conroy was more gravelly than ever but less nuanced, and Mark Hamill, whose Joker had been one of the highlights not only of his career but in the history of voice acting for animation, was curiously subdued, possibly because the character was now beyond his vocal range. Not so much a missed opportunity as one that should probably have never been tried - they endeavoured to render a desperately bleak tale a positive one for Batgirl, and it didn't quite take.