Released in 1971, "The Omega Man" takes place in 1976 when biological warfare between Russia and China has wiped out civilization and decimated much of the earth's population. The plot revolves around the main character, Robert Neville, who has received a serum that allows him to remain one of the last normal humans on earth after the apocalypse occurs.
During the day, Neville is forced to wander the vacant streets of Los Angeles, killing the albino cult members who have survived the biological plague, but have turned into freakish nocturnal mutants. At night, he must seal himself up in a large penthouse, fending off constant attacks by the mutant hordes that swarm the streets at night. Eventually, Neville is captured by leader of the mutants, Matthias, and put on trial. The mutants believe that Neville is a symbol of the science and technology that wiped out humanity in the first place and sentence him to be burned at the stake.
Neville is rescued by a woman named Lisa who has also somehow managed to survive the plague with a small band of normal humans. Neville and Lisa form a romantic partnership and continue to fend off the mutants while replicating the antidote to the plague. Lisa slowly succumbs to the plague and ends up joining the mutants.