The outcast Kai (Keanu Reeves) joins a group of Ronin, led by Kuranosuke Oishi (Hiroyuki Sanada), who seeks vengeance on Lord Kira (Tadanobu Asano) for killing their master and banishing the group. The Ronin embark on a journey whose challenges would defeat most warriors.
After a treacherous warlord kills their master and banishes their kind, 47 leaderless samurai vow to seek vengeance and restore honor to their people. Driven from their homes and dispersed across the land, this band of Ronin must seek the help of Kai (Reeves)—a half-breed they once rejected—as they fight their way across a savage world of mythic beasts, shape-shifting witchcraft and wondrous terrors. As this exiled, enslaved outcast becomes their most deadly weapon, he will transform into the hero who inspires this band of outnumbered rebels to seize eternity.