It's the battle of the secret spies. When pitted face to face, which agency comes out on top? Russia's KGB or America's CIA? Deadliest Warrior is the historical narrative series that each week culminates with a battle between two warrior groups, among them the Vikings, Genghis Kahn's Mongols, Japanese samurais, Aztec warriors, Roman gladiators and Navy SEALs. Also, experts use computer graphics to provide insight into what made these warriors so effective, and they analyse everything from their weapons to how they killed.