In what was billed as "The First East-Meets-West Western," Toshiro Mifune plays Kuroda, a samurai warrior who accompanies a Japanese diplomat to the United States. The diplomat has brought with him a golden, jewel-encrusted sword to present as a token of good will to the president, but as they travel by train through the west, they're ambushed by a pair of outlaws, Gauche (Alain Delon) and Link (Charles Bronson). Gauche and Link steal the sword, but Link leans the hard way about his partner's trustworthiness when Gauche double-crosses him and makes off with the booty. Since both Kuroda and Link have a grudge against Gauche, they warily join forces to track him down and return the sword to its rightful owner. Along the way, they have to deal with cultural conflict, Indian attacks, and encounters with beautiful women (played by Capucine and Ursula Andress). Given its cast and theme, Red Sun was predictably enough a major box-office success in Europe and Japan, but it passed through with little notice in the United States.
by Mark Deming synopsis