A young boy named Milo is going about his business, more bored than you could imagine. He doesn't like school and has nothing to do. (Or at least that's what it feels like). But in an exciting turn of events, he comes home one day to find a magic tollbooth in his room. He gets in his toy car, goes through the tollbooth, and finds himself in a magical place called the Lands Beyond. Now this is a story.
Milo starts by exploring a place called Wisdom and then passes through a region called the Doldrums, where everyone seems to be as bored as he was at home. He meets a watchdog named Tock, who joins him on his journey: together, they head to Dictionopolis where they meet a bunch of crazy characters who are obsessed with words. Yep, words. During a brief stint in jail (don't worry, it wasn't Milo's fault), Milo and Tock find out why Wisdom isn't so peaceful these days.
As it turns out, rival brothers King Azaz of Dictionopolis and the Mathemagician of Digitopolis kicked their sisters, Rhyme and Reason, out of the country – and it just hasn't been the same since. Milo decides it should be his mission to rescue these ladies. Why not?
After a very word-centric dinner in town (people in Dictionopolis eat their words… literally!), everyone bails and only Milo, Tock, and the Humbug are left with the king. After some deliberation, it is decided that the three of them will go on a journey to save Rhyme and Reason. But before completing their mission, they need to visit the Mathemagician to see if he'll give them the go ahead.
On their way to find brother number two in Digitopolis, they drive through the Lands Beyond and have a series of adventures: they meet a boy whose feet never touch the ground, a man who pretends he's multiple people, and a conductor whose orchestra injects color into the whole world. (Here's where we'll tell you, just go read it. It's just impossible to explain and quirkily as it happens.) Along the way, Milo learns that he needs to open his mind… quite a bit, in fact.
Next, the characters meet Dr. Dischord and the DYNNE, two individuals who are passionately interested in terrible sounds. From Dr. Dischord's home base, they travel into the Valley of Sound, where everything is silent. Through some tricky maneuvers, Milo manages to steal some sound and inject it back into the valley. He's just nailing it on this journey, huh?
After getting sidetracked when they jump to the Island of Conclusions, Milo, Tock, and the Humbug get closer to Digitopolis and run into the Dodecahedron. He accompanies them the rest of the way and shows them into a mine where numbers are brought out of the earth. They meet the Mathemagician, who explains the importance of numbers and just can't stop talking about math.
Using a bit of tricky logic, Milo gets the Mathemagician to grant them permission to move along toward Rhyme and Reason. They're almost there, but first, they have a few run-ins with some demons. Using the gifts he'd been given along his journey, Milo is able to help his gang make it to the Castle in the Air, where they meet Rhyme and Reason.
They all escape (in flight, thanks to the fact that time flies and Tock has a clock), and just in the nick of time, a huge army from the Kingdom of Wisdom comes to the rescue. The demons give up, and King Azaz and the Mathemagician welcome their sisters home. Hurray!
After a bit of celebration, Milo heads home. When he's back, he discovers that he was only gone for a couple of hours in his normal reality, even though he spent weeks in the Lands Beyond. Strange. The next day, the tollbooth's gone. But you know what? That's okay: by now Milo has opened himself up to the wonderful adventures and possibilities his own mind has to offer.