On a field trip set by his Social Studies teacher, Mr. Dimas, Joey finds himself lost in the city, and then enters a strange fog; when he emerges, everything has changed.

Jay explains to Joey that he belongs to an organization called InterWorld, whose task is to keep the altiverse in balance, by stopping the scientific force (Binary) from making worlds too scientific, while also stopping the magical force (HEX) from making worlds too magical.

He now begins an intensive course studying very advanced science and magic to prepare him for his new role as a member of the InterWorld.

After a few months, Joey and four other Walkers set out on a training mission, to retrieve some signal beacons from a more scientific earth.

The earth they go to turns out to be a "shadow realm", and is in fact a trap, set by the same people from HEX who captured him earlier.

With Jay's words in his head and Hue's help, Joey finds the airship where his team-mates are being held, but is again captured by the HEX, and taken to meet their leader, a hideous large goblin called Lord Dogknife.

In the centre of the room where his team-mates are being held is a large cauldron, where the HEX boil Walkers down to their raw essence, which is used as fuel for their transdimensional spacecraft.

Joey finds Hue, and despite an attempt by Lady Indigo to stop them, escapes with his team-mates through the gate and returns to the Interworld HQ.

Instead of congratulating them for their heroic work, however, the Old Man lectures them on all their wrongdoings in the Altiverse, but he allows Joey to stay, without wiping his memory, and soon the group sets out on another mission.

Suggesting to Gaiman an idea for a possible animated television series, they collaborated on the story and unsuccessfully tried to sell it to various studios, including DreamWorks, which was not interested.

[1] In June 2016, the plans to make InterWorld as television series were revived by Universal Cable Productions, in association with Hamilton producer Jeffrey Seller and his partner Flody Suarez.