Alicia Braga, Charlie Tahan, and Will Smith in I Am Legend. Courtesy of Warner Bros. Pictures

At night Neville leaves the playground of the city and fortifies himself in his brownstone townhouse facing Washington Square Park. The huge painted set of red brick with creeping trellis is the façade for a well-equipped fortress that contains all the creature comforts needed in being stranded from an outside world.

The walls of the living room are decorated with priceless works of art that Neville has plundered from the MoMa and the Metropolitan, including Henri Rousseau's "The Dream" and Van Gogh's "Starry Night." A Rothko painting adorns the weight room. The library is packed with artifacts belonging to warriors, war medals, medical certificates, and photos of Neville with army buddies. The shelves are lined with books on combat handguns, survival techniques, and global catastrophes. New York City maps plaster the walls, indicating neighborhoods with cleared roads and showing subway lines that are blocked. Herbs grow in a kitchen packed with canned goods. But metal doors and windows have been rigged to baton down at a moment's notice. Most ominously of all, the clocks have stopped at 7:25.

On set, the red light flickers, indicating that the set is active. Director Francis Lawrence (Constantine) calls for silence: "Rolling! Quiet everyone." Will Smith slowly opens a door and peers downward at something unseen. He moves with trepidation. This is the first time he will meet another human being since the disaster. He covers his mouth in shock.

In a later scene, Smith's character believes he is hallucinating and in a rambling interior monologue convinces himself of what he has just witnessed: "There are two real people in my kitchen and that was a shit first impression. You have to apologize… Take a shower. Change your clothes. Apologize. She'll understand."

The woman to whom he must apologize is Anna, played by Brazilian actress Alice Braga (City of God), the niece of actress Sonia Braga. For Anna, meeting Neville means "serendipity and hope." Her struggle will be to bring him back from the paranoid and neurotic state of mind brought on by his isolation. And together with others, they will have to vanquish the nocturnal mutants.

An Infected and Will Smith in I Am Legend. Courtesy of Warner Bros. Pictures

The creatures of that lurk behind every corner in I Am Legend may display vampire-like qualities, but they are more like the rapid flesh-eating machines seen in 30 Days of Night — they'll devour you alive, they won't stop to drink your blood, and they are not afraid of garlic. And they don't mind a cross. They have savage nocturnal survival instincts that appear to stop at nothing. Says screenwriter Akiva Goldsman: "They have a series of symptoms that are based on the idea that the adrenal gland has been fully opened. So they are an apparently more savage version of someone who is in a brain fever."