Cassie has an awesome boyfriend. Or so she thinks... Turns out he's a demon overlord in the Underworld out to make Cassie his Queen. Another guy at school comes in the picture. Galen, who is actually Cassie's guardian angel to keep her safe. The Overlord will have to sacrifice Cassie to send her soul to hell before he can make her his Queen.
[credit:] I think I got this from NaNoWriMo, but I didn't write it down for some reason