In the not-too-distant future, the aging gene has been switched off. To avoid overpopulation, time has become the currency and the way people pay for luxuries and necessities. The rich can live forever, while the rest struggle to negotiate for their immortality. A poor young man who suddenly comes into a fortune of time finds himself on the run from a corrupt police force known as the "time keepers".
The final installment finds Marty digging the trusty DeLorean out of a mineshaft and looking for Doc in the Wild West of 1885. But when their time machine breaks down, the travelers are stranded in a land of spurs. More problems arise when Doc falls for pretty schoolteacher Clara Clayton, and Marty tangles with Buford Tannen.
When a guardian angel – who invisibly watches over the citizens of Los Angeles – becomes captivated by a strong-willed heart surgeon, he ponders trading in his pure, otherworldly existence for a mortal life with his beloved. The couple embarks on a tender but forbidden romance spanning heaven and Earth.
