Betrayed: A House of Night Novel by P.C. & Kristin Cast

What's on the back of the book:
All any of us could talk about was Chris's disappearance and how bizarre it was that he had last been seen so close to the House of Night. I didn't want to believe it. But everything inside me said that the kid would be found, but he'd be found dead . . .

Things seem to be going pretty well for Zoey Redbird. She's settled in at the House of Night finishing school and is coming to terms with her incredible new powers. It all seems too good to be true. And guess what?

Someone has begun murdering human teenagers, and all evidence points to the vampyres at Zoey's school. Which means her first assignment as the leader of the Dark Daughters is finding out which one of her classmates or - gulp - teachers is a killer.

Sigh. And she thought her boyfriends (yes: plural) were going to be her biggest problem this year . . .

A piece from the book:
She took her hands from her face then and looked up at me, but I already knew who it was. I'd recognized her voice. And I also recognized what was happening to her. I forced myself to approach her calmly. She stared up at me. Her face was covered with tears.
'Come on, Aphrodite. You're having a vision. I need to get you to Neferet.'
'No!' she gasped. 'No! Don't take me to her. She won't listen to me. She - she doesn't believe me anymore.'
I remembered what Neferet had said earlier about Nyx withdrawing her gifts from Aphrodite. Why should I even mess with her at all? Who knew what was going on with Aphrodite? She was probably making some pathetic play for attention, and I didn't have time for this crap.
'Fine. Let's say I don't believe you either,' I told her. 'Stay here and have your vision or whatever. I have other things to worry about.' I turned to head into the stable, and her hand snaked out, grabbing my wrist.
'You have to stay!' she said through chattering teeth. Obviously, she was having difficulty talking. 'You have to hear the vision!'
'No, I do not.' I pried her vicelike fingers from my wrist. 'Whatever's going on, it's about you - not me. You deal with it.' This time when I turned I walked away more quickly.
But not quick enough. Her next words felt like she'd sliced them through me.
'You have to listen to me. If you don't your grandma will die.'