Fire — L.B. Gilbert

Invested with the powers of Mother Nature, four women have been charged with the almost impossible task of maintaining order in the supernatural world and-when the crimes are extreme-the human world as well.
Diana, a fire Elemental, is almost burned out. Alone in the world (save for her Elemental sisters), she takes satisfaction in punishing those who've strayed so far into the black they've disrupted the balance. But her contentment is increasingly short-lived as she struggles with the limitations of her ability. An Elemental can track murderers to the ends of the earth, but not before it's too late for their victims.
So when a child from a previous case goes missing, Diana is determined to find her. The only problem is, she may have to take on an entire coven of vampires to do it.