Development of an R-rated adaptation of the novel began in 2009; however, production was stalled due to the under-performance of DC's live-action adaptation of Moore's Watchmen. In 2011, Hamill expressed interest in reprising his role of the Joker for the adaptation, resulting in a fan campaign for its production. In 2015, producer Bruce Timm confirmed that an animated feature based on the book was in development. It is the first Batman film to be rated R by the MPAA.
The film premiered at the San Diego Comic-Con on July 22, 2016. Originally intended to be released directly on home video, due to its popularity, the film was instead released simultaneously in theaters and digitally on July 25, 2016 for a special one-night event, before a DVD and Blu-ray release on August 2, 2016. It grossed $4.4 million worldwide. Critical reception to the film was mixed. It received criticism for its prologue and its portrayal of Batgirl, while the adaptation of the source material was met with more mixed results. However, Hamill's and Conroy's performances as the Joker and Batman, respectively, received praise.
While out on patrol, Batgirl (Barbara Gordon) fails to stop a robbery, but manages to stop one criminal with help from Batman. Paris Franz, the robbers' leader and the nephew of a powerful mob boss, develops a dangerous obsession with her and starts sending her messages. After Franz tricks her into finding his uncle's dead body, Batman becomes concerned about her safety and takes her off the case, telling her that she will eventually be tempted to kill the criminals she pursues. Outraged, Batgirl attacks Batman physically and verbally, which leads to the both of them having sex. A few nights later, Batgirl tries to apologize to Batman, but he is ambushed by Franz and his men, prompting her to come to his aid. When she arrives and overpowers Franz, he makes her lose control and give him a savage beating, stopping just short of killing him. Realizing Batman was right, she retires from crime-fighting.
Later, Batman investigates a murder scene with Detective Harvey Bullock and concludes that the Joker, currently held at Arkham Asylum, might be behind the crime. He goes to Arkham to talk to him, only to discover that he has escaped and put a decoy in his place. Joker then attacks Barbara and her father, Commissioner James Gordon. He shoots her in the stomach, paralyzing her from the waist down, and takes Gordon to an abandoned amusement park. There, Joker strips him naked and subjects him to torture, including showing him photos he took of Barbara, naked and in pain.
The story is intercut with flashbacks of Joker's origin. It is revealed that he was once a lab technician who quit his job to become a stand-up comedian, only to fail miserably. Desperate to support his pregnant wife Jeannie, he agrees to help two criminals rob his former workplace. The criminals tell him that he has to use the Red Hood's mask and caped costume, secretly intending to frame him. During the planning, the police inform him that Jeannie and their unborn child have died in a household accident. Grief-stricken, he tries to withdraw from the plan, but the criminals strong-arm him into keeping his commitment to them.