When a group of boys accidentally stumbles on Gisborne’s weapons-testing site, all but one is taken prisoner. The resourceful escapee, Daniel, is able to elude Gisborne’s men and runs to Robin to raise the alarm. Robin is horrified to discover that Gisborne has developed an indestructible new suit of armour, made of special Damascus steel – an army wearing this armour would easily defeat King Richard and must be stopped!