In the coastal city of Velmoor, beneath its ordinary surface lies the Undercurrent — a shadow society where people bearing supernatural marks called Marca survive through blood contracts and carefully kept secrets. Saoirse Vane is a freelance bounty hunter with no guild, no past she admits to, and a reputation sharp enough that people pay extra not to ask questions. Her newest contract is straightforward on paper: locate and eliminate Caelum Drest, the last surviving heir of a bloodline that was supposed to have been erased seven years ago. The payment is unusually high. The deadline is tight. No questions allowed. Caelum Drest has spent seven years being hunted. What Saoirse does not know is that he chose her — researched her, waited for her, and made sure she would be the one hired. He needs a freelancer with no guild loyalty to help him retrieve a document that could destroy the entire Marca system. He did not plan on the Marca on her collarbone spreading faster every hour she fails to complete the contract. He did not plan on his bloodline ability stabilizing her without either of them understanding why. And he did not plan on being locked in a collapsing safe house with her for seven days, with every exit covered and the contract between them rewriting itself into something neither signed up for. Two people who learned to survive by never letting anyone close enough to matter. One city that wants them both dead. And a blood contract that turns out to be the least binding thing between them.