I Am Legend is the tale of one man, almost alone in the world after a virus wiped out most of the population. The human race turned into zombies shortly after this virus spread, which was originally designed to cure cancer, and so it's the job of scientist Robert Neville to find a cure for this dystopia, whilst trying to stay alive. A bleak mix of mayhem and loneliness ensues for Robert, who eventually finds a cure just as time is running out; the mutants - known as Darkseekers - are attacking his laboratory, so he tells his rescuers, Anna and Ethan, to hide in a coal chute, before detonating a hand-grenade to destroy an alpha-male Darkseeker. The only problem is that he's left in the explosion. He dies, only to become a legend when his hard work pays off. The thing about grenades though, is that they have a timer on them: if they exploded as soon as you released the pin, they wouldn't be much use. Not only does Robert not take advantage of this fact, he totally forgets that there is room for three people in the chute; it's alluded to in the film. He can quite easily hide with Anna and Ethan after killing the Darkseekers. Given how upset Robert had been earlier in the film though, losing his wife and daughter, and then even attacking Darkseekers after they infected his dog, he probably chose not to go with Anna and Ethan for a reason. It would have been a nicer ending had he been allowed to build a new life though.
