The last book in the C.S. Lewis series, Chronicles of Narnia. The Last Battle.
In the north of Narnia, a clever and greedy ape named Shift persuades a well-meaning but simple-minded donkey called Puzzle to dress in a lion’s skin (an echo from Aesop’s story of The Ass in the Lion’s Skin) and pretend to be the Great Lion Aslan. Using Puzzle as his pawn, Shift deceives many of the Narnians into serving the Calormenes and cutting down Talking Trees for lumber. The money will be paid into “Aslan’s” treasury, held by Shift, on the pretext that it will be used for the good of the Narnians.
Narnia has had peace and prosperity since the reign of King Caspian X, but Roonwit the Centaur warns Tirian, the latest king of Narnia, that strange and evil things are happening to Narnia and that the stars portend ominous developments. Tirian and his friend Jewel the Unicorn hear word of the death of the Talking Trees and rashly set out to confront the danger, giving Roonwit instructions to go and gather a small army to join them. Finding two Calormenes abusing a Narnian Talking Horse, they kill them both in a blind rage; ashamed, they give themselves up to “Aslan”. Awaiting judgement, Tirian recognises the farce that Shift has fabricated in league with the talking cat Ginger and the Calormene warlord Rishda Tarkaan: the lie that Aslan and the Calormene god Tash are one and the same. When he accuses the ape of lying, Tirian is tied to a tree for the night and will face judgment the following morning. He is treated by some of the woodland creatures, who are sympathetic to his suffering, but they can’t bring themselves to go against “Aslan.”
Tirian calls on Aslan for help and receives a vision of the “Friends of Narnia” gathered in our world – Professor Kirke, Polly Plummer, Peter Pevensie, Edmund Pevensie, Lucy Pevensie, Eustace Scrubb, and Jill Pole, though he does not know who they are. They also see Tirian and, though Tirian can’t speak to them, they guess he is a messenger from Narnia. A few minutes later by Narnian time – but a week later from their perspective – Jill and Eustace arrive in Narnia. They release the King and rescue Jewel. Puzzle, realising his folly, joins them.
A band of Dwarfs are also rescued, but their faith in Aslan has been shattered, and they refuse to help, claiming “the dwarfs are for the dwarfs”. Only one Dwarf named Poggin is still faithful to Aslan and joins the group. Tirian learns that Shift and Rishda have unintentionally summoned the actual Tash to Narnia when he and the others see him travelling north. Farsight the eagle arrives to help, bearing news that Roonwit and the Narnian army have all been killed in battle and the Calormenes have conquered Cair Paravel.
Tirian and his small force advance on the stable to expose the truth of Shift’s deception. Shift and Rishda plan to weed out the troublemakers by forcing them into the stable to “meet Tashlan.” But Ginger, sent in to aid in the deception, runs out in terror, having lost his ability to speak. Emeth, one of Rishda’s men and a devout follower of Tash, insists on seeing his god. Rishda tries to dissuade him, but Emeth enters the stable. Angry at the deception in the name of Tash, he kills another soldier who was stationed in the stable to murder the rebellious Narnians, but then disappears.
Outside the stable, Tirian’s group engages Shift and the Calormenes, but most of the remaining Narnians are all either killed or captured and sacrificed to Tash, by being thrown into the stable. Tirian throws Shift into the stable, and Tash, who has haunted the stable since Ginger briefly entered it, swallows the ape whole. This event frightens Rishda, who offers the remaining Narnians as sacrifices to Tash to avoid his god’s wrath. But Tirian, left alone and fighting for his life, drags Rishda into the stable and finds himself in a vast and beautiful land. Tash appears, seizing Rishda, and advances on Tirian just as the Friends of Narnia appear, all dressed as kings and queens. (Susan does not appear, they explain, because she has stopped believing in Narnia, thinking it was only a silly childhood game.) Peter in the name of Aslan orders Tash to return to his realm, and Tash vanishes with Rishda in his clutches. The faithless Dwarfs are present but cannot see they are in Aslan’s country; they perceive themselves to be locked in an actual stable. Aslan demonstrates that, without faith, even he cannot help them.
The kings and queens bear witness to the end of the Narnian world. All the inhabitants, living and dead, gather outside the barn to be judged by Aslan; the faithful enter Aslan’s Country while those who have opposed or deserted him become ordinary animals and vanish. The vegetation is eaten by dragons and giant lizards, and Father Time calls the stars down from the skies into the sea as it rises to cover Narnia. The land freezes when Father Time puts out the sun and the moon. Peter closes the door, and Aslan leads them to his country, telling them to go further up and further in. Soon they encounter Emeth; Aslan has accepted his faithful service to Tash because it was good and therefore truly done to Aslan, whereas Tash is only served by evil.
They find they are in a new, “real” version of Narnia. (Digory mentions Plato, whose Allegory of the Cave describes multiple levels of reality.) They move up a waterfall to gates where they are greeted by Reepicheep and meet/reunite with other characters from the earlier novels. They find they can see a real England, including the Pevensies’ parents, parallelling the real Narnia. Aslan tells them that the English friends of Narnia and the Pevensies’ parents have all died in a train crash. (Susan, who was not on the train, is the only surviving member of the family.) The series ends with the revelation that it was only the beginning of the true story, “which goes on for ever, and in which every chapter is better than the one before”.