<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> <P> Neville once again attempts to administer a potential cure to the infected woman in his laboratory, but the next night, a group of Darkseekers, who had followed Anna and Neville back the night before, attacks the house . Neville, Anna, and Ethan retreat into the basement laboratory, sealing themselves in with the female Darkseeker on which Neville has been experimenting . Discovering that the last treatment was successful, Neville tries to assess the situation as the alpha male deliberately rams himself against a glass door to break in . Neville draws a vial of blood from the woman he cured and gives it to Anna, before shutting her and Ethan inside a coal chute in the back of the lab . He then takes a grenade and kills the Darkseekers at the cost of his own life, saving the cure . The next day, before dusk, Anna and Ethan discover that her theory is right as they arrive at the survivors camp in Vermont . They are greeted by military officers and other human survivors before Anna is shown handing the cure to military personnel . </P> <P> The alpha male stops its attack on the glass door, making a butterfly - shaped smear on it . Neville realizes the alpha male is identifying the female upon which he was experimenting by a butterfly tattoo, and the Darkseekers simply want her back . Amazed that they have the intelligence to try to communicate with him, as he had previously believed the infected had lost all humanity, Neville puts his gun down and returns the female . After Neville wakes the female up, she cries upon seeing the alpha male and they rub heads . Neville softly apologizes, having realised that while the Darkseekers are no longer human, they still retain some of their humanity and emotions . The alpha male keeps the other Darkseekers back and orders them to leave . Shocked by the ordeal, Neville sits down for a moment in his laboratory, realizing that he was the monster in the Darkseekers' eyes . Looking over the pictures of his numerous test subjects, the implications of his research methods begin to dawn on him, causing him to feel remorse and relief at the same time . The following day, Neville, Anna, and Ethan drive away from the city under a new broadcast, recorded by Anna, with a message to any human survivors that they "are not alone". </P>

What happened at the end of i am legend
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