<P> In 2009, a genetically re-engineered measles virus, originally created as a cure for cancer, turns into a lethal strain which kills 94% of those it infects, mutates 5% into predatory, nocturnal and vampiric mutants, who are extremely vulnerable to sunlight, with only 1% immune . Three years after the outbreak, US Army virologist Lieutenant Colonel Robert Neville (Will Smith) lives an isolated life in the deserted ruins of New York City, unsure if any other uninfected humans are left in the world . </P> <P> Neville's daily routine includes experimentation on infected rats to find a cure to the virus and venturing through Manhattan to search for food and supplies . Also awaiting for potential human survivors each day for a response to his continuous recorded radio broadcasts, which instruct any uninfected survivors to meet him at midday at the South Street Seaport . </P> <P> Flashbacks reveal that his wife (Salli Richardson) and daughter (Willow Smith) died in a helicopter accident during the chaotic evacuation of Manhattan, prior to the military - enforced quarantine of the island in 2009, in which Neville stays behind on the island as military personnel . Neville's loneliness is mitigated by the companionship of his German Shepherd Samantha aka Sam (given to him by his daughter Marley as a puppy to protect him before she died in the helicopter crash), interaction with mannequins he has set up as patrons at a video store, and recordings of old television broadcasts . At night, he barricades himself and Sam inside his heavily fortified Washington Square Park home to hide from the Darkseekers . One day, while waiting for survivors, Sam follows a deer into a dark building . Neville cautiously goes in after her and finds the deer's corpse along with Sam, but the building is infested by a colony of Darkseekers . Both manage to escape unharmed and the attacking Darkseekers are killed by the sunlight . </P> <P> Neville finds a promising treatment derived from his own blood, so he sets a snare trap and captures a female Darkseeker from the colony building, while a male Darkseeker (termed "Alpha Male" in the script, and played by Dash Mihok) tries to go after them, but is blocked by the sunlight and returns to the shadows . Back in his laboratory in the basement of his house, Neville treats the female without success . The next day, he is ensnared in a trap similar to the one he used to capture the female; by the time he manages to escape, the sun is setting and he is attacked by infected dogs . Neville and Sam manage to eliminate them, but Sam is bitten in the fight . Neville injects her with a strand of his serum, but when she shows signs of infection, Neville is forced to strangle her to death . Heartbroken and driven over the edge of insanity by his dog's death, he ventures out and suicidally attacks a group of Darkseekers the next night . He kills a large number of Darkseekers but the rest overwhelm him and he is nearly killed, but is rescued by a pair of immune survivors, Anna (Alice Braga) and a young boy named Ethan (Charlie Tahan), who have traveled from Maryland after hearing one of his broadcasts . They take the injured Neville back to his home, where Anna explains that they survived the outbreak aboard a Red Cross evacuation ship from São Paulo and are making their way to a survivors' camp in Bethel, Vermont . Neville angrily argues that no such survivors' camp exists . </P>

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