Solstice - Joyce Oates

Monica Jensen surprises everyone who knows her - including her husband - when she accepts an offer to teach at a boys' school in Pennsylvania. As she moves into her new rambling house, Sheila Trask arrives, a wild-looking figure in jodhpurs, and invites herself in. Sheila, a painter, has long baffled the neighbours with her strange habits and eccentric demeanour. Monica can't
decide if she likes the woman, if she wishes her gone or if she feels a tug of powerful attraction.
Week by week, as Monica settles into the community and her teaching role, Sheila's exhausting attentions gradually become a source of energising insight: into Monica's own golden girl past, and into the dark Neitzschean insolence of Sheila's artistic vision.
As the solstice approaches and the evenings lengthen, together the women make a journey of intense friendship and sometimes frightening consequences.