After a whirlwind romance, divorcee Jessica Walker settles down to married life with her new husband, Neil.

When she suddenly loses her job, Neil suggests that they take the opportunity to visit his only relatives, two elderly sisters who live in an old rambling house on the coast. Jessica finds herself welcomed there with open arms.

At first she enjoys the holiday, relaxing and exploring her surroundings, but very soon a series of inexplicable events begin to disrupt her nights and days. As the disturbing incidents escalate, Jessica begins to question her sanity as well as her safety.

Fearful for her life, and desperate for answers, she knows that she must act quickly to uncover the truth.