From the first beats of its pulsating percussion score over the Raymond Carver quote that kicks things off through its stunning final shot, "Birdman or (The Unexpected Virtue of Ignorance)" offers an unrelenting immersion into the mind of a man being progressively swallowed by that most demanding and monstrous of beasts: the ego.

Director Alejandro González Iñárritu ("Amores Perros") shifts away from his standard preoccupation with hyper-serious ensemble pieces and shakes things up, with a jazzy and vibrant picture that takes a hatchet to Hollywood hypocrisy while fusing the backstage drama narrative with cutting-edge achievement.

The self-referencing begins at square one here, with the casting of erstwhile "Batman" Michael Keaton as Riggan Thomson, a one-time movie star best-known for helming the "Birdman" superhero franchise some 2½ decades earlier.

In a bid to make a comeback and achieve artistic respectability, Thomson has written and directed a Broadway adaptation of Carver's collection of short stories, "What We Talk About When We Talk About Love."

The movie, shot and seamlessly edited to appear as if much of the action unfolds over one single take, finds Thomson coping with an extraordinary heap of difficulties, from an egotistic co-star (Edward Norton) to his obstinate daughter (Emma Stone) and the persistent presence of his costumed alter ego, alternately growling confidence-boosting and deflating sentiments.

Filmed mostly inside the St. James Theater on West 44th Street, the movie is a technical marvel, with the camera soaring above the building and inside its windows and doors, storming through the maze of dressing rooms and low-ceilinged hallways and weaving throughout every contour of the stage. It's a cauldron of unrelenting energy and activity, showcasing the electric risks and severe pressures of mounting a theatrical production under adverse circumstances.

"Birdman" is also an adept satire that works on a micro level -- with its references to box office clout, the selfishness of critics and conflicting acting techniques -- and in a much bigger sense, with its tight close-ups on Thomson's increasingly strained face, nightmarish fantasies and haunting affectations (a homeless man shouts Macbeth's soliloquy), calling into question the very purpose and meaning of existence itself.

Dig below the flashy surface and what's left is a perceptive exploration and critique of the misguided ways we measure and determine our self-worth.

Keaton has insisted in interviews that he doesn't really relate to Riggan, and that the character is more of an autobiographical creation for Iñárritu.

Regardless, he's tapped into something truly special and deeply personal here, and emerged at the helm of a movie that's a hall of mirrors, to be sure, but one that reveals a lot about us all.

Birdman or The Unexpected Virtue of Ignorance)

3.5 stars

Directed by Alejandro González Iñárritu

Starring Michael Keaton, Edward Norton, Zach Galifianakis, Andrea Riseborough, Emma Stone, Naomi Watts, Amy Ryan

Rated R Playing at Angelika, Lincoln Square