Rebecca's narrative takes the form of a flashback. The heroine, who remains nameless, lives in Europe with her husband, Maxim de Winter, traveling from hotel to hotel, harboring memories of a beautiful home called Manderley, which, we learn, has been destroyed by fire. The story begins with her memories of how she and Maxim first met, in Monte Carlo, years before.
In her flashback, the heroine is working as the young traveling companion to a wealthy American named Mrs. Van Hopper. In her flashback, Maxim is staying at the same hotel as the heroine and her employer, and after knowing the heroine for only a few weeks, he proposes marriage. She accepts, and he marries her and takes her back to his ancestral estate of Manderley. But a dark cloud hangs over their marriage: Maxim's first wife, Rebecca, drowned in a cove near Manderley the previous year, and her ghost haunts the newlyweds' home. Rebecca's devoted housekeeper, the sinister Mrs. Danvers, is still in charge of Manderley, and she frightens and intimidates her new mistress. Despite the encouragement of the house overseer, Frank Crawley, and Maxim's sister, Beatrice, the heroine struggles in her new life at Manderley. She feels that she can never compare favorably to Rebecca, who was beautiful, talented, and brilliant--or so everyone says--and soon she feels that Maxim is still in love with his dead wife.
Manderley traditionally hosts a costume ball each year, and it is soon time for the gala to take place. Swept up in the preparations, the heroine's spirits begin to revive. But the ball ends in disaster: on Mrs. Danvers's suggestion she wears a costume that, it turns out, is the same dress that Rebecca wore at the last ball. Upon seeing the heroine, Maxim is horrified, and the heroine becomes convinced that he will never love her, that he is still devoted to Rebecca. The following day, Mrs. Danvers almost convinces her to kill herself, and she only breaks away from the old woman's spell when rockets go off over the cove, signaling that a ship has run aground. When divers swim near the grounded ship, they find the wreckage of Rebecca's sailboat, with Rebecca's dead body in the hold. This discovery prompts Maxim to tell the heroine the truth: Rebecca was a malevolent, wicked woman, who lived a secret life and carried on multiple affairs, including one with her cousin, Jack Favell. On the night of her death, Maxim had demanded a divorce, and she had refused, and told him that she was pregnant with Favell's child. Furious, he seized a gun and shot her, and then sailed out to the harbor in Rebecca's boat and sank it, with the body stowed safely inside.
This revelation restores the heroine's marriage, and enables her to finally shake off the burden of Rebecca's ghost. Meanwhile, however, the noose of justice tightens around Maxim: first, it is found that holes have been drilled in the bottom of Rebecca's boat; luckily the coroner delivers a report of suicide, rather than murder. But soon Rebecca's cousin Favell, certain that Rebecca did not kill herself, accuses Maxim of the crime. The local magistrate, Colonel Julyan, investigates, and finds that on the day of her death, Rebecca went up to London to see a Doctor Baker. Favell, Maxim, and the heroine accompany Julyan to London; the heroine is certain that Baker will reveal that Rebecca was pregnant, thus revealing Maxim's vengeful motive for murder. But instead, it turns out that Rebecca was dying of cancer, and that furthermore she was infertile; she had lied to Maxim about her pregnancy. Her terminal illness now supplies a motive for Rebecca's supposed suicide, and Maxim is saved. He and the heroine drive all night back to Manderley, stopping only once, when Maxim calls home and learns that Mrs. Danvers has disappeared. As they crest the ridge near the mansion, they look down and find it in flames.