An invalid matriarch manipulates her entire family.

The peaceful setting of the St. Aubyn family estate, known as Bastions, on England's western coast, masks the troubled state that exists within its walls. It is to this estate that Sherida Binyon has been summoned to serve as personal secretary to the wheelchair-bound poet Leah St. Aubyn. Soon after arriving at Bastions, Sherida is introduced to Leah's husband Mallory and her three stepchildren, Jane, Christine and Logan. As Sherida settles into her new home, Leah continues her flirtation with her physical therapist, Dr. Simon Crowdy. Simon, however, is in love with Jane. Prompted by the gossipy ramblings of her friend, Clara Brastock, Leah begins to have delusions that Sherida and her husband are having an affair. Later, when Leah denies Simon's request for permission to marry Jane, she is subjected to a frank analysis of her problems by the doctor. He tells her that she is exhibiting obsessions that are typical of those born under the astrological sign of the ram, Aries. He also accuses Leah of conditioning Jane to cling to her out of a perverse need to keep her "band of slaves intact." Stung by Simon's words, Leah exacts her revenge by lying to Jane and telling her that Simon confided in her that he thought Jane was getting too serious about their relationship. After attempting to destroy Jane and Simon's relationship, Leah next tries to drive a wedge between Logan and his new love, Catherine Woolton. She does not succeed, however, and the couple eventually announce their betrothal and intention to move to London. One day, while Logan is gone on a trip, Leah summons Catherine to the house and tells her lies about her estranged parents. This time, Leah succeeds in breaking up the couple when Catherine believes her claim that Logan fled to London after learning that there was insanity in her family. Devastated by Leah's words, Catherine vows never to see Logan again, then disappears. Her disappearance is soon explained by a suicide note that she wrote, which is delivered to Bastions by Catherine's stepfather. A search for Catherine leads Mallory and others to Echo Cove, where she is rescued from death by Mallory. Logan eventually discovers his stepmother's lies, and he and Jane both vow never to return to Bastions. Meanwhile, the confused Christine, having been told by Leah that Sherida is the source of the family's troubles, attempts to kill Sherida by poisoning her with an overdose of pills. With the extent of Leah's sinister machinations obvious to all, Christine is sent away to boarding school and the St. Aubyn family lies in ruin. Now driven to desperation by her family's rejection, Leah wheels herself to the edge of an oceanside cliff and falls to her death.