Robin the Bad (S04E05)

King John enlists a doppelgänger of Robin to commit misdeeds in Worksop, aiming to tarnish Robin's reputation and that of his outlaw companions. However, Marian uncovers the scheme and convinces the impostor to collaborate with the merry men to restore Robin's good name. Once their mission is accomplished, the look-alike sheriff becomes overly ambitious and attempts to storm the castle to confront King John, complicating matters for his double and putting their plans at risk.