December 1917. Germany opens the final, bitter round of the war with a new and deadly weapon in the struggle for the seas - the Vulcan sails from Kiel Harbour. To all appearances she is a harmless merchant vessel.
But her peaceful lines conceal a merciless firepower; guns, mines and torpedoes that can be brought into play instantly. The Vulcan is a commerce raider and her mission is to bring chaos to the seaways.