Survivor (1987)

Returning from outer space, an astronaut calling himself "The Survivor" finds a nuclear war has left the Earth as a desert wasteland. The Survivor spends 10 years roaming the desert wasteland in search of other people who may have survived the nuclear war. His 10 year search leads him to finding a woman who tells him about a rumored underground city that lies somewhere beneath the desert wasteland and The Survivor thinks the woman knows where it is. But the woman is kidnapped by a man named Kragg before she can reveal to him the location of the underground city. The Survivor goes in search of the underground city as he goes in pursuit of Kragg and his men and rescue the woman from her captors.