4x21 - The Adventures of Robin Hood

Boland, a former Crusader, defeats Will Scarlet and then Robin Hood in a sword fight and is only prevented from killing him by Maid Marian's prowess with the bow. Boland offers his services to the Deputy Sheriff, who makes him his lieutenant and takes sword-fighting lessons so he can kill Robin Hood himself and so take the glory to become Sheriff. Robin Hood accepts the challenge in the hope of revealing the Deputy Sheriff's true colours.