Plot summary
Karigan G'ladheon, a merchant's daughter, is cast out of her school in Selium by Dean Geyer following a duel in which she bested a wealthy aristocrat.
Running away from the shame of her expulsion, she travels into the forest called the Green Cloak. She meets a Green Rider (one of a group of legendary elite messengers in the king's service) who is dying with two black arrows protruding from his back. The Green Rider, F'ryan Coblebay, makes Karigan swear to carry a message to Sacor City for the 'love of her country', and there to deliver it into the hands of either Laren, the Captain of the Green Riders, or the king himself. He also orders Karigan not to read the letter for the sake of her life. Coblebay entrusts a second more private letter to her care also. As his life passes, he whispers with his last breath; "beware the shadow man...". She also takes the gold winged horse brooch that is the symbol of his office as a Green Rider.
Karigan, following her promise, rides the horse, which she calls "Horse" (whose real name is Condor), to Sacor City through perilous paths. Horse appears to have an uncanny ability to evade the various dangers Karigan encounters, always delivering Karigan to safety. During the journey, she meets many people, including the Berry sisters, members of the mystical, elf-like race of Eletians, and two traitorous Weapons (a special rank given only to the bodyguards of the king). Throughout her journey, the ghost of F'ryan Coblebay follows her, urging her on and providing help when desperately needed.
When she reaches Sacor City, she is hailed as a Green Rider, and she delivers both letters. The second seemingly less important letter, which Karigan felt justified in reading as it was not addressed to the king, was a love letter to the beautiful Lady Estora.
Karigan delivers the letter from F'ryan Coblebay but to everyone's dismay the letter appears to contain nothing of any importance. The Lady Estora, confused by inaccuracies in the letter delivered to her, approaches Karigan; who then takes the letter to Laren for closer inspection. The love letter is decoded to reveal a plot by his brother Amilton and one of the clan chiefs to kill King Zachary. Amilton, the elder brother of Zachary, was denied the throne due to his dishonorable character and eventually even lost the right to rule over the family province of Hillander due to his shameful behaviour.
There follows a desperate battle as Shawdell, an Eletian who has infiltrated the king's court and gained the trust of the crown, is revealed as the Shadowman F'ryan Coblebay warned Karigan of. During a dangerous battle Karigan, with the help of ghosts, wounds the rogue Eletian and he disappears. After the battle, it is discovered that Amilton, Zachary's disinherited older brother, has stolen into the castle and taken over. An elaborate and daring plan allows Karigan, along with the King and his retinue, to enter the castle through the underground tombs. Once inside, they make their way to the throne room and confront Prince Amilton. Shawdell (the rogue Eletian/Shadowman) has merged with Amilton and is taking him over. At this point, Karigan almost manages to sever the connection between Amilton and Shawdell and is transported to an in-between place where she manages to defeat Shawdell/Amilton and save the kingdom. After recovering from the ordeal, she goes home with her father, vowing to follow in his footsteps and become a merchant, leaving behind service as a Green Rider.
