Handlung

Every year 21 million people receive general anesthesia, and a vast majority of them go to sleep peacefully and remember nothing. 30,000 of these patients find themselves unable to sleep and are trapped in a phenomenon known as anesthesia awareness. They are awake.

Capital-investment firm chief Clay Beresford (Hayden Christensen) is in love with Samantha "Sam" Lockwood-Tunnel (Jessica Alba) but can't tell his mother Lilith Beresford (Lena Olin). Lilith and Clay come from a rich family. Sam is his mother's personal assistant.

Clay suffers from a heart condition & transplant will be carried out by Dr. Jack Harper (Terrence Howard) who had previously saved Clay's life and is now his good friend. Jack has 4 malpractice lawsuits against him and tells Sam that medical professionals get sued wrongly because the families of the victims don't know how to channel their grief. Jack tells Clay that there is a chance that he dies during surgery and a 50% chance that he dies from post-surgery complications in 10 years.

Clay's mother and her famous surgeon boyfriend Dr Neyer (Arliss Howard) try to dissuade him from going through the operation with a team of surgeons that have so many malpractice suits pending. Jack tells Clay to tell Lilith about Sam before the surgery. Sam is also pressurizing him, saying that they have been engaged for 6 months and yet cannot tell anyone. Clay doesn't like the intrusion by Lilith into his life & tells his mother about Sam. Lilith disapproves of Sam as a match for Clay. When Clay won't budge, she asks him to wait longer before marrying Sam, so he can get to know her. Outside Lilith's house, Clay proposes to Sam.

Clay asks Dr. Harper to arrange his elopement with Sam and they marry privately at midnight. While they are having sex, Clay receives a message that a matching donor has been found and he is asked to report to the hospital for his surgery. Lilith was already at the hospital (as she was also on the hospital call sheet), along with Neyer.

As the surgery approaches, Lilith again begs Clay to reconsider his surgery at the hands of Jack, but Clay trusts Jack & goes ahead. Neyer alleges that Jack already has 2 mortgages and 2 ex-wives and is under a lot of financial pressure. But no number of arguments are able to sway Clay. Jack's team includes Dr Eugene Puttnam (Fisher Stevens), Dr. Larry Lupin (Christopher McDonald), and Nurse Penny Carver (Georgina Chapman).

During surgery Clay encounters "anesthetic awareness", completely paralyzed, eyes closed, not being able to give any sign of their consciousness, but able to hear the doctors, and able to feel pain. To distract from the pain, Clay tries to focus on his memories of Sam, but also has flashbacks of his dead father being taken away. Clay has an out-of-body experience when Jack cuts into his chest cavity and uncovers a murder plot against him. Larry was not part of the conspiracy and Jack speaks to the others involved as soon as Larry steps out of the operating room. Jack suspects that Larry knows they have been pushing Clay down the donor recipient list so that the surgery only takes place after Clay marries Sam. Clay finds that Dr. Harper, one other surgeon and a nurse will inject his transplanted heart with a chemical Adriamycin that will cause it to be rejected. Dr. Harper has doubts when Sam comes in. She is the main person in the conspiracy.

The doctors want Clay to die because now that he and Sam are married, his millions will go to her, and in turn, pay for all the hospital's malpractice suits (later we find out that Sam used to be a nurse there). She proceeds to encourage Harper to go through with the plan and inject the transplanted heart. Clay is a rare blood type (O-) & they won't find a replacement in time.

As the surgery goes on, Sam tries to befriend Clay's mother Lilith. Sam reveals to Lilith that Clay and she are married. Sam says that for the past year, she was the one caring for Clay and all his medications. One of the other doctors' hits on Sam suggesting he has seen her before. Clay's mother is suspicious & finds that Sam was a nurse at the hospital under Harper. Lilith realizes the truth. Clay, during his out of body experience, is dejected and accepts his fate.

Clay's mother Lilith takes an overdose of some of her son's medicine, and calls her boyfriend, the prestigious surgeon, and tells him to come save her son. While Sam tries to get away with her actions, Dr. Harper feels guilty, and he holds onto proof so she can be arrested too. Her surgeon boyfriend returns to evict Dr. Harper, and, upon seeing Lilith's death, realized that she overdosed so that he could save her son (they had the same rare blood type). He then transplants the mother's heart into the son. Dr. Harper and his associates are arrested.

The new head surgeon announces that Clay has come back to life, as the new team stitch Clay's wound. Clay, in spirit, is still in the afterlife with Lilith and tries to take his own life to stay with his mother. Clay makes his new heart stop beating and the surgeons have to use the defibrillator in attempt to revive Clay.

His mother then proceeds to remind Clay that limbo with his mother and an afterlife with his father may not be that ideal. She reminds him that his father was an addict who was abusive to his son. During one such quarrel she had accidentally murdered her own husband as he was about to harm a young Clay.

This scene reveals the truth for Clay and connects his childhood flashbacks. After seeing this, Clay gives way to revival, and before the surgeons can shock his body again, Clay allows his new heart to begin beating. Clay opens his eyes when the surgeons remove the eye tapes while Harper ends his narrating with "He is awake."