Sydney Wells, at the start of the film, is a successful and classical violinist, although blind since the age of 5. She and her sister had been playing with fireworks, and they had been set off too close to her face, damaging her corneas.
Now, nearly 20 years later, Sydney undergoes a cornea transplant which causes her vision, albeit blurry, to begin returning. At first, she is confused and disoriented, unable to understand if what she sees is \"real\" or not. During her first night with her new eyes, her bedmate at the hospital dies, and Sydney, not understanding, watches her blurry figure being led away by someone else. During her stay, she also befriends a young girl named Alicia, who is there undergoing surgery for a brain tumor.
As time goes on, Sydney\'s vision begins to clear up and she struggles to understand the new world around her. She explains to her therapist, Paul Faulkner, that she sees visions of fire and death and people dying. Her bedroom walls keep changing to stone and back again, and she sees what appears to be the ghosts of people around her, including a young woman who walks right through her in the street just before she sees her body lying on the ground. The young woman stares at her dead body in disbelief before being led away by a shadowy demonic form. Although skeptical at first, Paul later feels that her strange visions are her mind\'s way of interpreting what it was never able to before.
When a Chinese diner suddenly explodes around her, she finds herself in the charred remains. She learns that the accident that burned the diner down occurred weeks prior, revealing that her visions are of the past. Fleeing back to her apartment, she viciously smashes every light source and covers her windows (and eyes). Days later, her therapist forces his way in and removes her blinds, telling her to return to the real world.
Upon discovering that the face that appears in the mirror is not her own (which she finds out through photographs of her in the past), she becomes desperate to figure out who and what is sending her these visions. She begs Paul for help and finally convinces him to drive her to Mexico (at the risk of losing his medical license), in order to find out what happened to her donor, Ana Cristina Martinez.
They go to Ana Christina\'s house where they meet her mother, Rosa Martinez, whose face looks slightly burned on one side. Rosa recognizes her daughter\'s eyes in Sydney. Sydney says that she has been having visions that she can\'t explain. Rosa states that her daughter could see death and that as a child she would look at houses and cry, and later in the day somebody in that house would die. The villagers believed that she was causing death instead of predicting it, and they branded her as a witch. The conversation ends when Sydney suddenly sees a shadow behind Rosa, so she quickly tells Paul to call an ambulance. Rosa immediately after suffers a heart attack. As Paul drives her to the hospital, Sydney walks into Ana Christina\'s room and sees more images. It turns out that the girl had committed suicide after failing to stop a factory fire that killed many of the people in the village and severely injured her own mother. Ana Christina had rushed into the factory and yelled for everyone to leave because they were in danger. The factory workers believed she was crazy and she was forcibly taken outside by two men who chained and padlocked the door from the outside to stop her from entering. Moments later, a furnace inside the factory exploded and most people died trapped in the fire by the padlocked door. After the fire, the deeply superstitious villagers, who had seen her crying outside the homes of people who were to die, believed she caused the disaster, and drove her to hang herself, calling her a witch and throwing stones at her.
Sydney and Paul return to the United States to discover the border is closed due to a high-speed chase on the other side. Dozens of vehicles are left stranded behind the closed gates. In the middle of the group of cars is a gas tanker with the number \"106\" on the front and a camper with a young girl in it; at the same time, many shadows move into the bus and take positions behind the people in it. Sydney then realizes that the images she keeps seeing - the number 106, bells, and a girl trapped in a fire - aren\'t of the past, but of the future. She rushes out of the car, shouting at everyone to flee, telling them a bomb is on the bus. The people listen and flee, just as a car smashes through the police barriers coming from the American side, and collides with the gas tanker. The tanker begins to leak gas and a spark causes the tanker to explode, destroying every vehicle in a chain reaction down the highway. Sydney\'s eyes are injured by flying glass during the explosion, which ultimately renders her blind again. She ends up glad to have used her visions to save lives and give Ana peace.