It's forty years since the world was poisoned and civilization crumbled. A man named Falk (Richard Harris) hides in an old steel mill with Miriam, this beautiful young blonde. She believes there is a place called Genesis, where things are growing and there's life. But along come The Ravagers, a group of men who take what they want. Falk does the best he can to defend himself but he's knocked off a girder and presumed dead. When he wakes up he finds Miriam dead and obviously multiply raped.
So he follows the Ravagers and kills one of them, which really ticks off the leader (Anthony James, who was the undertaker in BURNT OFFERINGS). The Ravagers start pursuing him. On his journey Falk first encounters a blind man who was kicked out of his clan, and is then stoned when he tries to get the guy some help. Then there's an old Sergeant (Art Carney) who still patrols a military installation/museum. They sort of become friends and the old guy teaches Falk how to use the weapons, like the machine gun. Then he takes him to a huge cave where there's an entire town of people called The Flockers. They trade amongst each other and are peaceful. Here Falk barters some sex from Faina (Anne Turkel) for some tobacco. But he's uncomfortable and he leaves--she and the Sergeant end up following him.
The Ravagers meet up with them and end up capturing the Sergeant. Falk and Faina make their way to the ocean where they meet another group of people who look well-fed and are clean. He forces them to take them to where they live, which is a huge ship anchored on the other side of a nearby island. They have 50 years worth of food, tools and electricity. A guy named Rann (Ernest Borgnine) is the leader and he will not let anyone leave--now including Falk. But some of the people do want to leave and heard Faina mention "Genesis". They believe Falk knows something he's not telling although he insists the place does not exist. The Ravagers are still after Falk and they attack the ship and start killing people. There's a battle and a dying Rann sets the ship on fire. Right before it explodes some people get out and escape to the beach. The next morning Falk leads the survivors off into the distance, saying that they are Genesis, a new beginning.
As post-apocalyptic movies go this is one of the better ones made, up there with THE OMEGA MAN, THE ULTIMATE WARRIOR and even the TV series ARK II.