In the 16th Century, a young Scotsman named Connor MacLeod receives a mortal wound in battle. When he survives certain death, his clan determines that he has made a deal with the devil and banishes him. Some years later, after marrying a woman named Heather, he meets his soon-to-be-mentor, Juan Sanchez Villa-Lobos Ramirez. He learns from Ramirez that they are both members of a group of immortals who can only die by decapitation and who must battle amongst themselves throughout the ages until only one is left to inherit the world.
In 1985, Connor lives in New York City as an antiques dealer named Russell Nash. After beheading a fellow immortal in a parking garage below Madison Square Garden, Nash becomes the target of a police investigation. Meanwhile, an ancient warrior known as The Kurgan (who had wounded Connor on the battlefield and killed Ramirez in the 1500s) and other immortals gather in New York for the final fight. In the end, there can be only one.