Darkness and Demon Song - M R Fournet

Marius Grey’s mom is back from the dead. After hunting monsters and performing forbidden spells, Marius is just happy she's there, helping him to take care of their Louisiana cemetery again. But it soon becomes clear that something has gone wrong. Marius's mother is growing more distant and strange things start happening around her. Worse yet, sometimes it feels like she’s a completely different person - one who definitely isn’t his mum. If Marius wants to save her, he’s going to need help. Serious help. Good thing he has a flesh-eating mermaid for a best friend and a classmate with extra-strong magic. Add in mysterious clues for new hunts, graveyard-hopping from Louisiana to Texas, and a tough ex-hunter he doesn’t know if he can trust, and it’s clear that Marius has his work cut out for him.