The Phantom Tollbooth by Norton Juster

This is a book that takes wordplay and turns it on its head. The only way to truly explain the brilliant writing of Juster is to go through the actual plot.

A bored little boy named Milo comes home one day to find an unusual gift waiting for him in his room: a miniature purple tollbooth. When he drives past it in a small car he is transported to the Kingdom of Wisdom, where he chooses to visit Dictionopolis, one of two capitals. He pays insufficient attention and becomes lost in the Doldrums, where thinking is not allowed, but he is found and rescued by the steadfast watchdog Tock who actually ticks, who joins him on his journey.

They arrive in Dictionopolis,where wonderful things happen where all the world's letters are grown in orchards and sold in a vast marketplace. Milo meet a real Spelling Bee who spells e-v-e-r-y-t-h-i-n-g and then talks to Faintly Macabre, the not-so-wicked Which (sic), who tells him about Wisdom's two rulers, King Azaz and the Mathemagician, and their adopted sisters, Rhyme and Reason. The two princesses were unable to settle the long-standing argument between their brothers over whether letters or numbers are more important and were banished to the Castle in the Air, high in the demon-infested Mountains of Ignorance. Milo then meets King Azaz the Unabridged, who agrees to allow the princesses to be rescued, providing his brother also agrees - a remote event, as they have not agreed on anything for years.

Milo and Tock leave Dictionopolis with the blustering Humbug, whom Azaz has sent along as a guide, heading towards the Mathemagician's capital of Digitopolis. Entering the Forest of Sight, they meet Alec Bings, a little boy who sees through things and grows until he reaches the ground; visit the twin cities of Reality and Illusions; and watch Chroma and his orchestra of color conduct the sunset. Moving on to the Valley of Sound, they meet Dr. Dischord, who dispenses unpleasant noises, and his smoky sidekick the Awful Dynne. In the valley proper, which is completely silent, Milo visits the fortress of the Soundkeeper, creator and cataloger of all sounds, who has withheld the valley's sounds because the inhabitants had stopped appreciating them. Milo steals a sound, which the people of the valley use to break open the palace's sound vault.

Milo and his friends continue on, taking a short detour to the Island of Conclusions, to which they jump after making unwarranted assumptions. Arriving in Digitopolis, they meet the Dodecahedron, a figure having twelve faces, each of which expresses a different emotion. He takes them to the Mathemagician, who shows them the Numbers Mine, where the world's digits are pulled from the earth like jewels. Milo tricks the Mathemagician into agreeing with his brother to release the princesses, whereupon the ruler takes them to the Mountains of Ignorance.
Milo, Tock, and the Humbug meet various demons. Milo uses gifts from all the people he has met in Wisdom to defeat the demons and the travellers climb to the Castle-in-the-Air, where the two princesses welcome Milo. The enraged demons chop off the base of the staircase, causing the Castle to begin to float away. Fortunately, time flies, with the result that Tock is able to carry the others back to earth. The combined armies of Wisdom drive back the demons. The two leaders welcome the princesses home and begin a celebration to mark their return.

Milo must also return home. The next day, he finds the tollbooth has vanished, leaving a note that he can now find his own way to Wisdom.

It is a wonderful little fantasy that was fabulous to read as a child and even better to read now that I am an adult.