Robert Neville, a doctor, due to an experimental vaccine, is the only survivor of an apocalyptic war waged with biological weapons. The plague caused by the war has killed everyone else except for a few hundred deformed, nocturnal people calling themselves "The Family". The plague has caused them to become sensitive to light, as well as homicidally psychotic. They believe science and technology to be the cause of the war and their punishment, and Neville, as the last symbol of science, the old world, and a "user of the wheel", must die. Neville, using electricity, machinery, and science attempts to hold them at bay.
Review :
I almost didn't bother writing this. After all, everybody has probably seen this movie and there really aren't a whole lot of other things to say about it other than "Gee, this is a classic and the Will Smith remake was crap."
Say what you will about his politics but Heston was an actor of some talent. He made enough movies that will outlive all of us that we have to step back and pay him that compliment at least.
This movie was pretty close to the book (And if you haven't read "I am legend" I suggest you do). It still get's the ending wrong, but that is less important than you might think for this movie. After all, none of the adaptations are perfectly true to the book.
Of course, it has a sad ending - as almost all of the 1970's sci-fi/horror movies did. I wonder what it was about the 70's that led filmmakers to not be able to imagine a good ening to these types of stories? Whatever it was, it led to some really great movies. And this was one of them.