You know Michael Keaton's crime-fighting vigilante days might be over when he goes from "Batman" to "Birdman."

The former Caped Crusader will be joining Emma Stone, Naomi Watts and Zach Galifianakis in "Birdman," the new dark comedy from writer-director Alejandro Gonzalez Innaritu, according to Heat Vision.

"Comedy," whether it's dark or otherwise, may not be the genre that immediately springs to mind when it comes to the man who brought us such brutal examinations of the human condition as "21 Grams" (which also starred Watts) and "Babel." However, Innaritu's new project sounds like it will indeed be showcasing his lighter (-ish) side.

"Birdman" sounds like a movie for theatre people as it follows a washed-up former comic book hero actor (Keaton in a bit of meta-casting) and his attempt to win back his former glory by mounting a stage production of a Raymond Carver short story. As with most movies about trying to put on a play, there are madcap complications, including a difficult leading man whose ego threatens to derail the entire endeavor.

Emma Stone will be playing Keaton's daughter and assistant, with Naomi Watts playing one of the actresses and Zach Galifianakis as a conniving producer. The leading man has yet to be cast, though it would be a stroke of brilliance if it were Keaton's old "Batman" nemesis, Jack Nicholson.

Production is set to commence in April after Stone wraps principal photography on "The Amazing Spider-Man 2." Meanwhile, Keaton recently wrapped the "RoboCop" reboot and Galifianakis is preparing for the unveiling of "The Hangover Part III," opening May 24.