‘Batman & Bill’ unmasks the dark secret behind the Dark Knight’s creation

For a long time, the legendary character Batman harbored a secret darker than any of his comic book superhero counterparts: his true origin story.

In a New York apartment in 1939, Bob Kane and Bill Finger huddled over a drawing board and came up with what has become one of the most popular fictional characters of all time. But as author Marc Nobleman reveals in Hulu’s first original documentary, “Batman & Bill,” Kane went on to acquire fame and glory as Batman’s sole creator while Finger faded into obscurity, dying alone and penniless in 1974. As Nobleman says in the documentary, “Bill was Batman’s secret identity.”

“Batman & Bill” offers a compelling slice of pop culture history, charting  Nobleman’s journey as he researches material for his 2012 book, “Bill the Boy Wonder: The Secret Co-Creator of Batman.”

Kane and Finger had similar backstories of their own. Both the sons of Jewish immigrants, they changed their names to guard against the anti-Semitism of 1930s New York, giving them a better chance in the job market — Robert Kahn became Bob Kane and Milton became Bill.

As “Batman & Bill” showcases through artfully nostalgic comic book panels, Kane and Finger attended the same high school (though they met later in life, at a party) and both aspired to be cartoonists. Their paths diverged during the height of the Great Depression, as the unassuming Finger set aside his dreams to take a job as a shoe salesman, and the more openly ambitious, bombastic Kane snagged work at DC Comics, then known as Detective Comics.

Goaded by the success of “Superman,” the brainchild of two other children of Jewish immigrants, Joe Shuster and Jerry Siegel, Kane decided to cash in with a comic book invention of his own. “Batman & Bill” reveals that in his original design, the “Bat-Man” wore a red bodysuit and goofy-looking detachable wings, until he called his friend Finger to help brainstorm the rest.

Finger developed most of the elements of the character that are so recognizable today: Batman’s real identity as Bruce Wayne, the honorific “the Dark Knight,” Batman’s two-page origin story and characters such as Robin, the Joker, the Riddler and police commissioner Gordon, plus the name Gotham City.

But Kane claimed all the credit for himself and there was no way for Finger to contest it — no contract or paper trail of any kind.

“It was one man’s word against the other,” Nobleman says in the documentary. “It was two guys in an apartment in the Bronx in 1939, when most people had much bigger things to worry about than who’s coming up with this guy dressing up as a bat.”

Nobleman, a longtime comic book aficionado, felt a moral calling to get Finger the credit he deserved. “It became a crusade,” he says. But to challenge the juggernaut DC Entertainment for a Finger credit line, Nobleman needed to find a living heir for a legal pathway to redress. Channeling Batman, Nobleman used his detective skills to uncover Finger’s sparse family history, and that eventually led him to Finger’s only grandchild, Athena.

Born in Portland, Ore., Athena Finger grew up in Boston with her mother and now resides near Fort Lauderdale, Fla., with her son. She teaches math at the local college and produces oversized paintings on the side. “Just trying to be creative,” she said over the phone.

Athena’s parents separated when she was a baby, and she saw her father, Fred Finger, Bill’s only child, only on occasion before his death when she was 15.

“My dad would tell me about his father and what he did,” she said. “He would tell me about how his dad wrote all these great stories for Batman and how he created the character. He had fond memories of his dad writing.”

Though Fred and Bill’s relationship became strained when Fred came out as gay, Fred continuously strove to get his father public recognition as the co-creator of “Batman,” especially with the release of the 1989 Tim Burton film starring Michael Keaton.

But when Fred got sick, Athena explained, “he couldn’t spend energy trying to fight for something when he’d been told ‘no’ for so long. And that’s one of the reasons it took me so long to pursue getting him credit myself, because after my father passed away, I was told it was going to be extremely difficult and very consuming, [both] financially and emotionally.”

Growing up, Athena wasn’t involved in the comic book world, though she knew of her unique family history from her father and named her dog Bruce Wayne. Buoyed by Nobleman’s efforts and the fan support he had garnered, Athena reached out to the DC offices herself.

“Once Marc had approached me, I realized that there was actually a community of people who knew the truth,” she said. “And that was new for me.”

Several of these passionate and well-known fans are interviewed in “Batman & Bill,” such as filmmaker and podcaster Kevin Smith, producer Michael Uslan, pop culture psychologist Travis Langley and an array of comic book historians.

As a result of the collective efforts of the community of Batman fans, the morning of Sept. 18, 2015, brought some welcome news to Athena Finger and Marc Nobleman: DC resolved to add Finger’s name as co-creator of the original Batman character in the credits for the television show “Gotham” and any future Batman-based projects.

“Batman v Superman: Dawn of Justice,” which opened in theaters four months later, was the first big-screen adaptation to carry the new credit line: “Batman created by Bob Kane with Bill Finger.” Asked how it felt to see her grandfather’s name in its rightful place, Athena paused. “How do you describe that?” she mused, and it’s clear that the moment is bittersweet.

“It was exciting,” she said, “but I wish there were other people here to see it.”

The moment came with mixed feelings, but it represented a triumphant moment for the underdog — and the successful pursuit of justice. Just the way Batman would have intended.

“Batman & Bill” debuts May 6 on Hulu.