Banished from their hometown, two mismatched teens must survive a dense wilderness haunted by dangerous and ancient biomechanical gods. Ever since her mom mysteriously vanished, teenager Bear has been alone. A pariah and an outcast in her small, backwater town she desperately longs for someone who understands her. Instead, she gets stuck with Mouse! Unlike Bear who values peace, quiet, and avoiding conflict, Mouse is headstrong, outspoken, and impossibly stubborn. It also doesn't help that Bear blames Mouse for the disappearance of her mom, close to a decade ago. Needless to say, our teenage protagonists do not get along. After an incident with highly forbidden technology gets them both banished from town, Bear and Mouse are forced to flee into the treacherous Iron Wilds. This sprawling jungle is overrun with gargantuan god machines called Demons, remnants of a long-forgotten war.

This makes being shunned from civilization the equivalent to a death sentence--well, for anyone except Bear, who possesses the mysterious ability to quell the Demons by revealing a birthmark on her hand. The deeper Bear and Mouse venture into the Iron Wilds, the more they learn about Bear's connection to the Demons. It's a secret that threatens to tear Bear and Mouse's uneasy alliance, and their entire world, apart.