Carter was a former soldier under King Richard on the Third Crusade, who became an assassin in England and was hired by Sheriff Vaisey to kill Robin. He has sworn revenge on Robin Hood, believing him to be responsible for his brother's death in the Holy Land. After ingratiating himself with the outlaws, Carter ties up Marian and the gang before attacking Robin, who knocks him out and takes him into Locksley to show him the suffering caused by killing. Carter escapes and corners Robin in a barn, where they fight and Carter tells Robin why he hates him so much. Robin realizes the mistake he's made and explains that Carter's brother Thomas had caused his own death through reckless disregard of orders, not through any fault of Robin's to save him. When Carter refuses to believe that, saying his brother was a war hero, Robin tells him his brother's last words: "Don't tell my family I cried. Tell them I was laughing on the wrong side of my face." Carter cries, "He always said that! How do you know that?" Robin lays down his sword and says, "Kill me now if it will give you peace of mind." Carter can't do it, and the gang bursts in to find Carter weeping on Robin's shoulder.
The gang then tries to help Carter collect his promised £500 reward by drugging Robin so that he appears dead, and sending him into the castle. While the sheriff is exulting over Robin's apparent death, Carter gives Robin the antidote, Robin wakes up, and they both escape. The sheriff refused to give Carter the money, even at sword-point. Carter then returns to the Holy Land, to visit his brother's grave and apologize for all the killing he did in his memory, and to carry Robin's message to King Richard that was supposed to have been delivered by Roger of Stoke.
He makes a brief reappearance in the season two finale ("We Are Robin Hood!"), to rescue Robin, Marian, and the gang from the desert, where they had been tied up and left to die by King Richard as the result of a misunderstanding perpetuated by the sheriff and Guy of Gisborne. He is killed by the sheriff himself in this episode while trying to protect the king from an ambush by the Saracens.