Exiled from a prestigious martial arts school for being too successful in a duel with an aristocrat, Karigan is considering repeating the fate of her father - becoming a mercenary and guarding merchant caravans. But Fate itself makes the choice for the girl... She will have to become one of the Green Horsemen - secret royal messengers carrying messages on which the fate of the country - and perhaps the whole world - depends. From now on, she is the bearer of a mysterious magical power that protects every green horseman, and... a new target for the creatures of Darkness, again and again trying to destroy her. Now she is guarded by the ghosts of previous messengers... Now she is being hunted by a mysterious shadow man... But the king's message must be delivered on time!