In 2054, Nema and her friends Adam and Izzy are Real Worlders who live on the Earth's surface. One day a strange man named Moojag leaves the three with a series of riddles and an invitation to a place called Gajoomdom. When they follow the riddles, they find themselves in a strange underground land.
Moojag and the Auticode Secret contains examples of:
- Dedication: "For Jake, Catti, Erato, Alexander, and all the late, self, and misdiagnosed autistics."
- Flooded Future World: Most of England has been underwater since the tidal surge caused by global warming ten years ago. Nema and her friends live on a small island in what used to be Surrey.
- LEGO Genetics: The "pofs" were children with various genetic disabilities who were involved in experiments that aimed to cure them using cicada DNA. It seemed to work at first, with the children becoming healthy and incredibly strong, but then they grew cicada wings, stopped growing, and became increasingly hyperactive. They now live in Gajoomdom and are seen as eternal children with the inability to care for themselves or make their own decisions.
- Long-Lost Relative: Nema's older brother Monzi went missing around the time of the Surge. Because of his autism, he was taken to Gajoomdom and made to work as a coder with the other auts. He now goes by Moojag.
- Neurodiversity Is Supernatural: In addition to the twenty-one senses that most people have, autistics have a twenty-second sense that allows them to read others' emotions and predict future events, but most have buried it because they either weren't aware of it or couldn't control it. When the people running the world learned about the super sense, they were afraid of what autistics might be able to do, so around the time of the Surge, the Conqip took a large number of autistic children underground so they can use the problem-solving abilities enabled by the twenty-second sense to design technology that will allow the Conqip to live in luxury. The Auts form an underclass whom the Conqip feel free to insult and mistreat, even though their lifestyle depends on them.
- Sdrawkcab Name: Moojag is backwards for Gajoom, which refers to robots that look like giant sticks of candy.
- Speaks in Shout-Outs: Moojag's friend Wats' dialogue consists largely of titles of Beatles songs.
- You Are Number 6: The Gajooms all go by numbers like G6 and G21.