Captain Nathan Algren (TOM CRUISE) is a man adrift. The battles he once fought now seem distant and futile. Once he risked his life for honor and country, but, in the years since the Civil War, the world has changed. Pragmatism has replaced courage, self-interest has taken the place of sacrifice and honor is nowhere to be found - especially out West where his role in the Indian Campaigns ended in disillusionment and sorrow.

Somewhere on the unforgiving plains near the banks of the Washita River, Algren lost his soul.

A universe away, another soldier sees his way of life about to disintegrate. He is Katsumoto (KEN WATANABE), the last leader of an ancient line of warriors, the venerated Samurai, who dedicated their lives to serving emperor and country. Just as the modern way encroached upon the American West, cornering and condemning the Native American, it also engulfed traditional Japan. The telegraph lines and railroads that brought progress now threaten those values and codes by which the Samurai have lived and died for centuries.

But Katsumoto will not go without a fight.

The paths of these two warriors converge when the young Emperor of Japan, wooed by American interests who covet the growing Japanese market, hires Algren to train Japan's first modern, conscript army. But as the Emperor's advisors attempt to eradicate the Samurai in preparation for a more Westernized and trade-friendly government, Algren finds himself unexpectedly impressed and influenced by his encounters with the Samurai. Their powerful convictions remind him of the man he once was.

Thrust now into harsh and unfamiliar territory, with his life and perhaps more important, his soul, in the balance, the troubled American soldier finds himself at the center of a violent and epic struggle between two eras and two worlds, with only his sense of honor to guide him.