The Rule of the Damned (Titan Syndicate Saga #1) by Stephanie Storm:
 
Remember all those scary stories you were told as a child...the ones where the monsters are hiding under your bed?

They aren't just stories.

We're real.

We’re behind some of the world’s deadliest catastrophes and continue orchestrating them from the shadows. Most humans don't know that we exist, and we aim to keep it that way. Remember the Salem Witch Trials? That’s what happens when our secret gets out. Human fear becomes deadly and drives them to enact unthinkable violence.

The Druids. The Undead. The Rogues. The Sorcerers.

We’re four families that are united in our mission to run the Underworld. While we may not like each other, we set aside our differences to keep the underworld running.

Until an Heir is murdered.

Now, I’m determined to find the murderer before the trail of bodies leads the humans to our front door, and everything we’ve kept hidden is at risk.

—-

Vampire Diaries meets Gossip Girl in the first instalment of a new action packed urban fantasy series following morally grey characters and the criminal empire they run. Family, power, and mythical monsters collide as the families are faced with a string of unsolved murders that threaten to expose them all.