The film is set in the years 2009 and 2012. It opens in the fall of 2009 with a television news broadcast featuring Doctor Alice Krippin (Emma Thompson), who claims that she has created a cure for cancer with a 100% success rate. Dr. Krippin says that the cure was created by altering the measles virus. In September 2012, U.S. Army virologist, Lieutenant Colonel Robert Neville (Will Smith) is left as the last healthy human in New York City and possibly the entire world. A series of flashbacks and recorded news broadcasts reveal that the genetically re-engineered measles virus (referred to as K.V. or Krippin virus) mutated into a lethal airborne strain that spread worldwide and killed 5.4 billion people, i.e. 90% of humanity. Of the 600 million survivors, only 12 million people possessed a natural immunity to the virus. The rest degenerated into bald, pale, aggressive beings referred to as "Darkseekers" (the DVD subtitles refer to them as hemocytes – actually a cell type found in an insect\'s immune system), who have a painful intolerance to UV radiation. This forces them to hide in buildings and dark places during the day. The "Darkseekers" exhibit increased speed, agility, aggression, and strength, as well as higher pulse, metabolism and respiration rates, and increased body temperature. Despite their primal behavior, the Darkseekers seem to retain some basic problem-solving intelligence, animalistic cunning and the capacity to organize themselves. The remaining immune human population were killed by the infected.
Neville\'s daily routine includes experimentation on captive infected rats to find a cure for the virus, and trips through an empty Manhattan to collect supplies from abandoned homes and hunting deer that moved into the city. He also waits each day for a response to his continuous recorded AM radio broadcasts, which instruct any uninfected survivors to meet him at noon each day at the South Street Seaport. Neville\'s isolation is broken only by the companionship of his German Shepherd dog Samantha ("Sam"), interaction with mannequins he has set up as patrons of a video store, and recordings of old television broadcasts. Neville drives a Ford Mustang Shelby GT500, using it to aid him in hunting deer in the streets of Manhattan.
When one of his experiments on rats shows a promising treatment, Neville sets a snare trap and captures an infected woman. Back in his laboratory, located in the basement of his heavily fortified Washington Square Park home, Neville attempts to treat the infected woman, without success. Later, after finding one of his mannequins in front of Grand Central Terminal, he is caught in a trap and passes out. When Neville finally regains consciousness and manages to get free, it is dusk, and he is attacked by a pack of infected dogs. Although Neville and Sam manage to kill the dogs, one of the infected dogs bites Sam (although dogs are unaffected by the airborne strain of the virus, they are still affected by the contact strain). Neville takes the wounded Sam back to his lab and attempts to cure her, but she begins to exhibit symptoms, and he is forced to kill her, as she becomes aggressive.
The following night, after burying Sam in a cornfield, and overcome by grief and rage, he attacks a group of the infected. Despite killing a large number of Darkseekers, the infected overwhelm Neville and nearly kill him, but he is rescued by a pair of immune survivors, Anna (Alice Braga) and a young boy named Ethan (Charlie Tahan), who have heard his AM broadcasts.
Flashbacks reveal that his wife Zoe (Salli Richardson) and daughter Marley (Willow Smith) died in a helicopter accident during the chaotic evacuation of Manhattan, immediately prior to the military-enforced quarantine of the island in December 2009.
Anna and Ethan take the injured Neville back to his home, where Anna explains that they are making their way to a putative survivors\' camp in Bethel, Vermont. When Anna claims that their meeting wasn\'t coincidence, but part of God\'s plan, Neville argues that given the devastation incurred by the Krippin virus, there can be no God.
Suddenly, the Alpha Male leads a group of infected in an attack on the house, having followed Anna and Neville back the night before. The Darkseekers force Neville, Anna, and Ethan to retreat into the basement laboratory. They seal themselves in a room with the infected woman, where they discover that Neville\'s treatment is working: the subject has reverted to a more human form. The Alpha Male begins to crack and break through the acrylic glass separating them by ramming it. The cracks come to resemble the wings of a butterfly, at which point Neville remembers his daughter mentioning a butterfly the night she died, and her voice rings through his mind. He notices a butterfly tattoo on Anna\'s neck and takes a sample of the infected female\'s blood and gives a vial of it to Anna, saying, "The cure is in her blood... I think this is why you are here." He pushes Anna and Ethan into an old coal chute and shuts them inside. He then sacrifices himself to save their lives, using an M67 hand grenade and running into the cracked acrylic glass shield to kill the Darkseekers.
Anna and Ethan escape to Vermont and locate the survivors\' colony, where Anna hands over the cure. Before the credits roll, the ending scene in the movie depicts the survivors colony from a bird\'s-eye view. The scene is voiced over by Anna, who claims that the survivors are Neville\'s legacy, as Neville became a legend for finding a cure. Alternate ending
The tone of the film\'s ending was altered before the film\'s release, especially the stand-off between Neville and the infected in his laboratory. Visual effects supervisor Janek Sirrs recounts the original ending starting with the stand-off: "At that point, Neville\'s—and the audience\'s—assumptions about the nature of these creatures are shown to be incorrect. We see that they have actually retained some of their humanity. There is a very important moment between the Alpha Male and Neville. The Alpha Male slapped his hand on the glass and smeared it revealing a butterfly shaped imprint." Neville realizes that the Alpha Male is identifying the infected woman he was experimenting on by a butterfly tattoo, and that the Alpha Male wants her back. Demonstrating that he will cease fighting and return her, Neville is allowed to approach them, with the Alpha Male ordering the infected not to touch him. Neville brings the Alpha Female back to consciousness, still infected, due to him having removed the cure, and the Alpha Male embraces her; David Schaub stated, "Then, when Neville finally turns the Alpha Female over to the Alpha Male, there is this little love moment between the two of them." Neville and the Alpha Male then exchange stares; Neville apologizes to them, which the Alpha Male acknowledges before the infected leave. He then looks at the photos of the infected he has experimented on and killed, and he realizes that he is the monster of their legends: the infected think of him as someone who hunts down and kills their people. The original final shot follows Neville, Anna, and Ethan as they cross the remnants of the George Washington Bridge in hopes of finding other survivors, accompanied by a recording from Anna telling possible survivors that there is hope, and Neville knows the compounds of the cure, meaning he can recreate it and help humanity survive and rebuild, thus establishing his legend. This ending has been claimed as being closer to the original novel.

Releshed Date  14 - December - 2007