Seventeen-year-old Krescent Dune is buried under the weight of her dead parents' debt and the ruinous legacy they left behind. The only way she can earn enough money to escape her unforgiving island is by battling monstrous creatures in an underground fighting pit.

After a fight goes terribly wrong, she's banned from the pits. Now hopeless, she is offered a deal: in exchange for the erasure of her debts, she must join and protect a hunting party for a rescue mission deep within the mining caves beneath the island.

Krescent is determined to keep her head down and fulfill her role as the dutiful bodyguard, even though she is trapped underground with her childhood enemy and a company of people who would gladly kill her if they knew who her parents were. As they come across creatures she believed only existed in legends, it becomes clear they are in far more danger than she could have imagined.

But someone doesn't want her to make it out alive. And she'll have to figure out who before she's left alone...in the dark.