4x11 - The Adventures of Robin Hood

Martin, a former Crusader friend of Robin's who saved his life seven years before at the crusade, masquerades as one of Robin's gang. He begins robbing innocent travellers entering Sherwood forest, including Friar Tuck, and fatally wounds John Dale in his home. Martin wants to join Robin's band, and when he learns that Friar Tuck and Marian know Robin, he has the upper hand. Robin has to make him leave, bearing in mind the debt he owes this man.