From the desert wastelands of Erda rises the ancient city of Monstrocity. Steel and glass towers soar above a tangled mess of railways and tunnels. Above is a paradise for the rich and successful, while below, in the stinking depths, the poor labour ceaselessly to keep from starving.

In the misty chasms of Down Below, one child looks up and for a brief moment catches a glimpse of blue sky. The boy, Kinsey, realises that all he has to do is climb.

He is never seen again.

Teenagers Tourmaline and Tyler reach out to disgraced weapons designer Dr Margot Mossberg for help. But then the doctor's latest experiment is stolen, and the three must embark on a harrowing journey through the labyrinthine alleys of Down Below, into the lairs of mad and exiled scientists.

While some of these scientists are benevolent, others are downright evil and plotting to dominate the entire city!