In 12th century England, the country is weakened by decades of war and under the threat of a French invasion. After the death of King Richard the Lionheart during a battle in France, a skilled archer named Robin Longstride, along with his band of marauders, stumbles upon a dying knight, Sir Robert Loxley. The knight implores Robin to return his sword to his father in Nottingham. Posing as the dead knight, Robin assumes the identity of Loxley and returns to England. He delivers the sword to the knight's blind father, Sir Walter Loxley, who asks him to continue impersonating his son in order to prevent the family lands from being seized by the crown.

Robin agrees to the charade, stepping into the life of Loxley, which includes a strained relationship with Loxley's strong-willed widow, Marian. Despite initial mistrust and disdain for each other, Robin and Marian's relationship begins to turn into a deep mutual respect as Robin takes on the role of the protector of Nottingham's people. They struggle not only against the harsh taxation of the newly crowned King John but also against the looming threat of an invasion led by the treacherous Godfrey, who aims to stir up civil unrest in order to weaken England's defenses for his French allies.