Infernal Magic (Demons of Fire and Night, 1)

She's forgotten her past. Too bad her past won't return the favor. Ursula can't remember a single thing from before three years ago, so she has to keep her life simple. All she wants is to earn enough money for rent - and maybe a bit left over for a new pair of boots. But on her 18th birthday, all hell breaks loose, quite literally, when a hellhound shifter shows up in her kitchen. Kester's lethally gorgeous, and he's come with a terrifying message: Ursula owes her soul to a demon. No one seems to care that she doesn't remember striking that deal. Thrust into the middle of a war between the gods of fire and night, Ursula fights her way across New York - and through the fae realm - to survive. Along the way, she must reclaim her magical knowledge and her long-forgotten skills with the blade if she wants to escape eternal damnation.