Nat Cassidy's highly commercial, debut horror novel Mary, blends Midsommar with elements of American Psycho and a pinch of I'll Be Gone in the Dark.

Mary is a quiet, middle-aged woman doing her best to blend into the background. Unremarkable. Invisible. Unknown even to herself.
But lately, things have been changing inside Mary. Along with the hot flashes and body aches, she can't look in a mirror without passing out, and the voices in her head have been urging her to do unspeakable things.
Fired from her job in New York, she moves back to her hometown hoping to reconnect with her past and inner self. What she finds instead are visions of terrifying, mutilated specters come with increasing regularity, she begins auto-writing strange thoughts and phrases, and her investigations reveal that these experiences are echoes of an infamous serial killer.
Then the killings begin again.
Mary's definitely going to find herself.
A Macmillan Audio production from Tor Nightfire.