The Farthest Shore takes place years after the other books, when Sparrowhawk has become Archmage and a head of the magic school on Roke. It tells the story of magic fading out of Earthsea. The story begins with Arren, a young prince from Enlad, who is coming to Roke to report trouble. He meets with Sparrowhawk (or Ged, as in the previous books) and he reports that spells no longer work in the Outer Reaches. Many of the wizards on Roke don’t believe him, as to them magic is un-killable, but Ged had fought dark forces himself as a boy and he knows that it is true. There is no a quick fix that Arren can take home. The archmage and the prince have to set off on a voyage around the world to seek out the sources of loss.
They leave Roke Island to find the answer on the boat Lookfar. They head south to Hort and they meet a drug addled wizard called Hare. They are almost tricked by him to follow him into the Dry Land to their deaths, which makes them realise that a powerful wizard has the influence on Hare and many others.
The journey continues as they visit the island of Lorbanery and they head west and south to the furthest parts of the Reaches. When the dark wizard is having increasing influence on them, they encounter the Raft People who live on great wooden rafts in the open ocean. The Raft People are so far unaffected by the spreading evil that Ged and Arren recover their strength there.
They encounter the dragon Orm Embar, who tells the archmage to sail to Selidor, which is the traditional home of the dragons. Ged was told that the dark wizard is there and the dragons are powerless to defeat him. They travel over the open ocean and they manage to survive the madness of dragons and land in Selidor. Orm Embar is already waiting for them, but he has lost the power of speech. Here, they find the wizard in a house made of dragon bones at the extreme western end of Selidor - the end of the world.
Ged recognises the wizard as Cob, a dark mage whom he defeated many years before. Cob's act to cheat death has opened a breach between the worlds which is sucking all the life out of the world of the living. When Ged confronts Cob, Orm Embar helps him and destroys the enemy’s physical body. The part of Cob’s body, which cannot be killed, gets into the Dry Land of the dead. Ged and Arren decide to follow him. Ged manages to defeat Cob and closes the breach in the world. However, he pays a high price as he sacrifices all his magic power in the process.
After coming back to the world of the living and after a dreadful journey over the Mountains of Pain, the dragon Kalessin carries them back to Roke island. Arren is left on Roke, but Ged is taken to Gont, his home island. The prediction of the last King of Earthsea many centuries before "He shall inherit my throne who has crossed the dark land living and come to the far shores of the day" has been fulfilled. Now it is Arren who is crowned as King Lebannen.