At the beginning of Green Rider Karigan has been suspended from Selium for besting a fellow student Timas Mirwell, son of Lord-Governor Tomastine II. She has run away from the school with the intention of reaching her father in Corsa before a letter from the Dean of her school. On the way, she runs into a Green Rider, a magical messenger of the king. He is gravely wounded by two black arrows and with his dying breath, charges her with the duty of delivering a message to the King of Sacoridia. For Karigan, it is the beginning of a journey fraught with danger and intrigue that will forever change her.