Kyunosuke, a farmer's son and descendant of samurai, dreams of leaving the farm and winning fame and fortune as a renowned warrior. When a retainer of the ambitious Lord Yasutaka shows up one day and offers to employ Kyunosuke, even advancing him money for clothing and weapons, it seems his fondest wish will be fulfilled.
But this apparently lucky turn of events conceals a less palatable reality: Kyunosuke was hired only because he bears an uncanny resemblance to Lord Yasutaka. He is to be the third of the lord's "shadow warrior" doubles. Although he receives samurai training, it's only to make his impersonation of Yasutaka more effective. The pay is good, but since his existence must be kept a secret he gets few opportunities to enjoy his new station in life.
When at a critical moment in a battle Lord Yasutaka is wounded in his left eye by an arrow, Kyunosuke takes his place and wins the day. His reward: he and the other doubles get to lose their left eyes,too. As the distinctly unpleasant side of his duties makes this indelible impression on the Third Shadow Warrior, he begins to rue the day he left his father's farm.
Shortly after his eye is removed by the court surgeon, a sneak attack by a treacherous ally throws the lord and Kyunosuke -- now the only surviving double -- together as the two flee for their lives. Yasutaka is wounded again in the desperate fight to get away from the castle, receiving a cut which nearly severs his left arm. In terrific pain, he orders his double to finish the job and strike off his arm.
Kyunosuke reluctantly complies, then realizes that if he succeeds in getting Yasutaka alive to the castle of another ally, he'll have to have his arm amputated, too. He naturally rebels against this prospect, and tells Yasutaka so. Raving and cursing, Lord Yasutaka tries to cut him down for his disobedience; Kyunosuke kills his master in self-defense and leaves his body for the crows.
But Kyunosuke will not escape his fate so easily. While trying to flee the province, he's recognized on the road by another fugitive, the same retainer who first hired him. Kyunosuke is given a choice between immediate death, or taking Yasutaka's place for real.
The Third Shadow Warrior understandably chooses the latter option, but again, he will live to regret it. In the Japanese tradition of "cruel histories", maintaining this illusion will cost him everything: his identity, his family, his love. Though he is supposed to be a lofty samurai lord and commander of an army, every attempt to take charge of his destiny ends with Kyunosuke further ensnared and confined, a puppet dancing to another's tune.
Besides having a very Buddhist take on the nature of illusion, the film has quite a bit to say about class distinctions as well. Beautifully shot in black-and-white in a widescreen format, with an excellent cast -- particularly Ichikawa, who provides two very convincing performances as both the arrogant, brutal Lord Yasutaka and conflicted Kyunosuke -- Third Shadow Warrior in no way deserves its apparent obscurity.
