A handsome young man wakes up to a female voice telling him to open his eyes. He drives to an empty city. He wakes again, this time to a woman in his bed. He tells her not to leave him messages on his alarm clock.
From a prison cell in Madrid, the 25-year-old man, César (Eduardo Noriega), tells his story to psychiatrist Antonio (Chete Lera) while wearing a prosthetic mask. Flashbacks reveal the following events: Good-looking César is attractive to women. At his birthday party, he flirts with Sofía (Penélope Cruz), his best friend Pelayo’s (Fele Martinez) date. Later, he takes her home and stays the night, but they do not sleep together. The next morning, César’s obsessive ex-lover Nuria (Najwa Nimri) pulls up outside Sofía’s flat, offering him a ride and sex. On the way to her house, however, she crashes the car with the intent to kill them both. César survives the crash but is horribly disfigured, beyond the help of cosmetic surgery, so he decides to wear a mask to conceal his face. Sofía cannot bear to see him and tries to keep her distance.
After César’s disfigurement, he begins to have a series of disorienting experiences. Drunk, César falls asleep in the street. On awakening, everything has changed: Sofía now claims to love him and the surgeons restore his lost looks. But as he makes love to Sofía one night, she suddenly changes into Nuria. Horrified, César smothers her with a pillow and kills her. Yet everyone else believes Nuria was indeed the woman everyone else calls Sofía, and he is imprisoned for her murder.
While he is confined to the prison, fragments of his past return to him as if in a dream. It is revealed that, shortly after falling asleep drunk on the street, César signed a contract with Life Extension, a company specializing in cryonics, to be cryogenically preserved and to experience extremely lucid and lifelike virtual reality dreams. Returning to their headquarters, under supervision by prison officers, he discovers they specialize in cryonics with a twist: “artificial perception” or the provision of a fantasy based on the past to clients who are reborn in the future. He had committed suicide at home a few months after falling asleep drunk on the street and was placed in cryonic suspension. His experiences from about the midpoint of the movie onward have been a dream, spliced retroactively into his actual life and replacing his true memories. At the end of the film, he decides to wake and be resurrected. Convinced his life since the drunken night in the street is simply a nightmarish vision created by Life Extension, César leaps from the roof of the company’s high-rise headquarters, and wakes to a female voice telling him to relax and open his eyes.