Two insatiably curious young girls must develop an uncontrollable currency to break the power of the elite that rule their society.

In a world roamed by giant beasts and newly intelligent species, humanity has retreated into fortified hive cities. Here, millions labour to keep ancient technology alive, aided by steam-powered artificial intelligences. Two girls, Leodie, a bold, adventurous and loyal friend, and Wimax, a cautious, intelligent and curious inventor, do not fit well in the highly structured society. Driven by curiosity, they reactivate long-dormant computer networks. Now everyone can send and receive messages and communicate securely around the all-powerful elite of the hive city. The reaction from the ruling queen’s court is swift: Lady Talox, the intelligent, ruthless and commanding leader of the court, orders them to stop their inventions. Shocked and afraid but also angry, Wimax and Leodie are calmed down by their tired caretaker, Lenpou, a wise and gentle woman. Together, they explore the history of humanity and discover inconsistencies in the official records of the court. Seeking to know more, they discover books that the court has sought to bury. These show them how currencies have been used by rulers throughout history to enact control. They come up with the idea to break the financial control of the court by inventing an uncontrollable currency.

They seek out their adopted Uncle Satomi. A compulsive and distracted inventor, his humanity was forever lost when he became embedded inside a mechanical body. Leodie and Wimax combine their ideas with Satomi’s technical mastery. Together they explore how economics work in the hive and invent a new type of digital currency: the ghost leaves. But the court has monitored them, and they are exiled. They are left, scared and very alone, in the Green Zone, infested with giant insects.  

Barely surviving, they find Kratharsus Rex, an ancient and fierce battle scorpion with very high opinions about himself. Leodie and Wimax befriend the lonely colossus, and together they hatch a plan to rescue Lenpou and Satomi. This requires the help of the wolf spiders: giant, intelligent arachnids. Guided by Kratharsus Rex, they meet Captain Patches, an aged, adventurous and charming spider commander. In the spider village, Leodie and Wimax are reunited with Lenpou. She escaped the hive and shows them a new bold side of herself. In two spiderlings, Leodie finally finds someone who can match her unbridled need for adventure. With Wimax turning into a reluctant leader, they manage to convince the spiders that helping them is in their own best interest: left unchecked, Lady Talox will seek to dominate the whole region.

With their new friends, Leodie and Wimax embark on a daring mission to break into the hive sanctum. Here dwells Queen Sarthe, a terrifying cyborg, her humanity sacrificed to produce eggs. Parachuting down the central air shaft of the hive, they arrive undetected and break into the sanctum. Fearful but determined, the two girls confront the cyborg that is also their mother. Shocked but also curious, the queen agrees to talk. They tell her everything they have learned about economics, power and inequality and manage to convince her to arrest Lady Talox and consider economic reform in the city.