Hell Bent - Hound of Hades, #5

Another day, another demon... When humans start showing up dead after visiting Manhattan's hottest new club, Mal's mission seems simple enough: find whatever supernatural critter is responsible, and show them the consequences of intruding on Hades's territory. Mal isn't complaining-between moving in with Bastian and dealing with the fallout of Melinoë's attack, she could use an easy job. But the more she investigates, the less simple it becomes.
Because someone wanted Mal to find out about these deaths. Someone with the power to command creatures that even the gods fear. Someone with a plan that could tear apart the divine and mortal realms alike-a plan that is missing only its final piece: Mal herself. Mal would never betray Hades. At least that's what she always thought. But everyone has their price... and somebody may have found hers.