He used to be the star of a big superhero movie franchise, where he played a Batman-like character called…Birdman. But the dude is now a washed-up fifty-something, trying to write, direct, and star in his own play. (The play's an adaptation of the short story, "What We Talk About When We Talk About Love," btw. And it's super-thematically important.)
When we first see Riggan, he's in his tighty-whiteys and floating a couple feet in the air. This is our first clue that something is, um, off…but whether it's the movie or Riggan himself that's screwy, we're not quite sure.
Riggan leaves his comfy levitation spot and heads down to the stage, where rehearsals are in full swing. Then—kablammo—his costar Ralph is hit in the head by a light fixture that falls from the ceiling. This is good news and bad news. The good: Ralph—who's talentless—won't be acting anymore. The bad: they need a new actor. Luckily, Lesley, one of the play's four actors/actresses, says her lover Mike wants the part. Everyone's excited.
And, at first, Mike's great. Okay, maybe he doesn't wear underwear and is pretty incredibly crude, but he's already improving the play's writing and proving to be a very talented actor. But Mike's really into authenticity—when the character he's playing is supposed to be drunk, Mike figures that the best way to get into the role is to actually get tanked. Then, when Riggan replaces his gin with water during the first preview, Mike throws a hissy fit and the preview ends early.
It's too late to let Mike go, so Mike and Riggan have a talk where they debate the various merits of popularity and respect and prestige and truth. (This movie gets deep, guys.) We also meet Tabitha, a snobby critic whose reviews will make or break Riggan's play.
Later, Riggan runs into his daughter Sam. Cute family moment ensues? Hardly: Sam, who's barely out of rehab, is smoking some pot. Drama ensues. She yells at Riggan and tells him he is irrelevant, which hurts Riggan a lot because being irrelevant is what he's most afraid of.
The next preview is better, but during the sex scene Mike wants to actually get it on with Lesley…who definitely doesn't want to have sex in front of eight hundred strangers. The audience laughs at Mike's erection but Lesley doesn't think it's funny. She and Mike break up and Laura, our fourth actor, comforts her in their dressing room. Laura and Riggan are dating and Laura's upset that Riggan is, well, kind of jerk.
The next morning, Mike and Riggan get in a fight because a) Riggan is a little unstable b) Mike is a little arrogant and c) Mike went behind Riggan's back and did an interview that wasn't too kind to Riggan.
Still upset, Riggan goes back to his office and destroys it with his telekinesis. Yep, you heard that right. Oh, and Birdman, a deep voice in his head, tells him he never should have left the movie business because now he's a joke. Birdman also encourages him in the whole room-destruction thing.
Meanwhile, Sam and Mike meet on the balcony and play some Truth or Dare. Sam maybe wants to fool around, but Mike is worried he won't be able to perform (unlike on stage, where he didn't have any problems).
But the next day Sam tries again and seduces Mike. Riggan sees them kissing and steps outside to cool off. But he gets locked out of the theater with his robe caught in the door and has to ditch the robe and walk through the streets in his underwear to finish the final preview, which actually ends up working out except for the unwanted popularity of Riggan's mostly naked body.
That night Riggan talks to Tabitha in a bar. She tells him she's going to destroy his play. Riggan's upset and gets totally drunk, passing out on the street.
When he wakes up, Birdman is there. He's not a voice anymore; he has a physical form: a dude in a bird suit. Riggan maybe-almost jumps off a building, flies around town (like, he's literally flying through the air), and somehow makes it back to the theater in time for the first real show.
Was that a dream? Is he still drunk? We don't know.
At any rate, everything goes well, even the talk with his ex-wife where he apologizes to her for everything bad he's done. Then it's time for the final act. Riggan's character in the play is supposed to pretend-kill himself to end the play…but the gun Riggan loads beforehand definitely isn't fake.
Riggan shoots himself onstage…
…but misses his brain and hits his nose.
He wakes up in the hospital with a new nose and a whole ton of buzz. Everyone—critics and theater-goers alike—loved the play. It's a huge success. Alone in the hospital room, Riggan says goodbye to Birdman and climbs out his window. When Sam comes in she doesn't see him anywhere, but finally she looks out the window and looks up. She smiles.