Gravebooks (Nightbooks, Bk. 2)

But when Natacha, the witch who held him captive for his scary stories, appears again one night, Alex realizes he's trapped in a nightmare—literally. She's found a way to enter his dreams with a new, terrifying familiar named Simeon. And they once again want Alex to write. Transported to a story graveyard with his best friend, Yasmin, Alex will have to complete an original scaary story each night. But what does Natacha plan to do with his finished stories? And what makes a story good enough? While Natacha might have control of the beginnings, only Alex has the power to write the ending.