In this third instalment of the 'Back to the Future' series, hero Marty McFly (Michael J. Fox) must go back in time to the Wild West of 1885 to rescue his friend Doc Brown (Christopher Lloyd), who he has discovered is due for a fatal showdown with one of bad guy Biff's nasty ancestors. Meanwhile, the good Doc has fallen in love with a newly arrived schoolteacher (Mary Steenburgen).