It is 922 AD. Ahmed Ibn Fahdlan (Antonio Banderas) is an Arab ambassador travelling through Northern Europe with his mentor Melchisidek (Omar Sharif). They chance upon a band of Vikings, who are licking their wounds after an attack by mysterious creatures. A fortune teller prophecies that unless the Vikings can find a 13th warrior then they are doomed to destruction. This warrior must be an outsider, and soon Ahmed is enlisted to join the clan, but further attacks rapidly place the band under mortal threat.