Joss Whedon has exited the Warner BrosBatgirl, a DC stand-alone movie that he came aboard last year to write, direct and produce. The deal was first made public last March, and would have seen the writer and director of Disney/Marvel’s tentpole blockbuster The Avengers join a rival comics universe of movies.

He said today essentially he couldn’t crack the story of the Gotham heroine, who as been in DC Comics lore since the late 1960s.

“Batgirl is such an exciting project, and Warners/DC such collaborative and supportive partners, that it took me months to realize I really didn’t have a story,” Whedon said in a statement. “I’m grateful to Geoff and Toby and everyone who was so welcoming when I arrived, and so understanding when I… uh, is there a sexier word for “failed”?

Whedon knows of heroines, having created Buffy The Vampire Slayer, Dollhouse and Firefly.

The original Batgirl was set up as Barbara Gordon, the daughter of Gotham Police Commissioner Jim Gordon. Rosario Dawson voiced Batgirl who had a prominent role in WB’s hit animated The Lego Batman Movie.

No word from the studio on what will become of the movie. Warner Bros has another female-centric DC pic in the works in Gotham City Sirens, which will focus on the Harley Quinn character played by Margot Robbie in Suicide Squad. David Ayer, who helmed that pic, will also direct Sirens.