Hidden Magic by Linsey Hall

Cass Clereaux is a FireSoul–one of the unlucky few to inherit a piece of a dragon’s soul. It gives her a deadly, forbidden magic, but at least it helps her find treasure. When Cass is blackmailed by a criminal overlord who holds her life in his hands, things get rough. He wants a pair of rare daggers hidden inside a deadly temple. If she doesn’t get them, she’s dead. But when Cass gets into the temple, what was supposed to be a normal job is decidedly…not. And surviving it might be impossible.