Chronicles of Narnia Series, Book 7

During the last days of Narnia, good King Tirian faces the firecest challenge to any Narnian King's rule ever. Many Narnians think they have seen the great Aslan, but he doesn't behave the way they had expected. The ugly Ape who guards this false Aslan allows him to be seen for only moments at a time, and says that all Narnians have been commanded by the Lion to work for the cruel Calormenes.