In the gripping opening scenes of "I Am Legend," we are plunged into a world overtaken by a devastating virus, where humanity teeters on the brink of extinction. Set in a post-apocalyptic New York City, the first 50 minutes of the movie introduce us to Dr. Robert Neville, played by Will Smith, as he navigates the desolate landscape haunted by mutated creatures. Your task is to craft a narrative focusing on the external conflict Neville faces as he grapples with both the physical dangers of the infected and the psychological toll of isolation. You may tell this story from first or third person, which must be at least 500 words.