Spirit Witch. Witches of Mountain Shadow, #3

Strange things happen in Mountain Shadow - especially when you break a deal with a demon. Fiona defeated a dangerous enemy, but she left his bargain with the demons unfulfilled. Her town is under supernatural siege, and its mortal inhabitants are terrified. Wesley and Gabriel are at odds after Gabriel's startling revelation. To make matters worse, Fiona has begun to experience one brother's emotions while trying to date the other.
When an unwelcome witch returns from the dead, Fiona knows a powerful demon is behind it. It's up to Fiona to dissolve the pact or risk total annihilation. To save her town, she'll have to access a power she didn't know she had - one that's both seductive and terrifying.