Bad Moon Rising | Isabelle Lightwood 
"In a time when the world was young and demons ran unfettered across the face of the Earth, the Powers That Be chose a young woman, one girl in all the world to combat that forces of darkness. Upon her death, the power passed to another, and another. Down, over the millennia, with each girl inheriting the power of her predecessor: the power of the Slayer."
[Slayers Book One]
[Shadowhunters season 1]
[Extended summary inside]
[Cover filter credit to @graphicgodesses]