Autumn Gothic by Brian Bowyer

In San Francisco, Sierra falls in love with her favorite author. After learning that Vivian Kane grew up in a haunted house, she persuades Vivian to take her to the mansion in West Virginia, where they encounter a savage entity known as the Sorceress of Night. In Los Angeles, Delilah—a celebrated musician—kills humans as sacrifices to the ancient gods of death. When Mark—her guitar player—discovers her evil ways, she gives him two choices: leave California, or become her next victim. He flees, and then Delilah changes her mind, killing people across America while pursuing him as he travels east. After she tracks him to a mansion in the mountains of West Virginia, monsters both human and inhuman collide on Halloween night.