Nightfall — Katharine Marlowe

High school teacher Rebecca Leighton narrowly misses hitting a student seeking assistance when his friend's car breaks down very late one rainy night. Soon after starts a series of escalating acts of vandalism and harassment. Life turns ugly and incomprehensible. With the help of a plainclothes detective on the local police force, Rebecca tries to determine just who could be behind the ongoing torment. And if the bizarre events in her own life aren't disturbing enough, something's wrong with her best friend, Agnes, the head of her department at school. Agnes's behavior is growing increasingly more peculiar, and Rebecca is deeply worried because Agnes seems to want to pretend everything is just as usual. In trying to conceal all this from her widowed mother, and in trying to fight off the detective's increasing appeal, Rebecca feels that, daily, she has less and less control--of anything.