Japan 1945. One of the most high octane, dynamic ninja films ever made. The shadow family was considered specialists in espionage and assasination and masters of superb ninjitsu fighting techniques. Making their armour and weapons with mysterious tough extraterrestrial metal called 'invincible steel'. Which was harder than any other on Earth. After many years of warfare, their armour and weapons have been lost. We follow 'Red Shadow' and his fellow ninja on their latest mission to investigate a mighty new weapon hidden in the armoury of Kyogoku castle and sense increasing danger as they sneak into the castle only to face the Negoro ninja who are waiting for them. Could this be the end of the shadow family?