Rebecca opens with the narrator describing a dream she has had about a house called Manderley; it is a house that she has previously lived in but that is now, for some reason, reduced to a shell. We learn that the narrator is living in exile with her husband, both of them deeply nostalgic for England and for Manderley, but both relieved to be free of a situation which had brought fear and stress.
We then backtrack to the narrator's first meeting with her husband, Maxim de Winter, whose ancestral home is Manderley in the English west country. We learn of her whirlwind courtship with him, whilst working as a lady’s companion in Monte Carlo, and of how she returns with him to Manderley as his second wife. His first wife, Rebecca, she hears, drowned in a sailing accident.
Now "the second Mrs de Winter" (we never learn her first name), the narrator recounts her difficulties in settling at Manderley. Treated with hostility and disdain by the sinister housekeeper, Mrs Danvers, she is overcome with shyness and awkwardness as she struggles to fulfil the domestic and social obligations of an upper-class wife. She also becomes increasingly and disturbingly haunted by the almost tangible presence of her predecessor, and from conversations with those who knew Rebecca comes to perceive her as a beautiful, talented, socially-adept individual who was universally loved and admired. Most of all, she becomes convinced that Maxim is still deeply in love with Rebecca, and that she herself is of little significance to him.
When a fancy-dress ball is held at Manderley to celebrate the new Mrs de Winter’s arrival, she is persuaded by Mrs Danvers (whom she now knows ‘adored’ Rebecca) to wear a particular outfit. Unknown to Mrs de Winter, it is identical to an outfit worn by Rebecca at a previous ball, and when she appears it causes horror and consternation, particularly on the part of Maxim de Winter. Overcoming her distress, Mrs de Winter manages to change her outfit and struggle through the ball, but she becomes convinced that she has now alienated her husband for ever.
A day later, however, a diver finds the boat which Rebecca was sailing when she drowned, with a skeleton in the cabin. Previously, it was believed that she had drowned trying to return to shore, and a body found in the sea had been identified by Maxim de Winter as that of Rebecca. Following the boat’s discovery, Maxim confesses to his wife that he murdered Rebecca and took her to sea in her boat, which he then sank. He reveals that he hated Rebecca who, although she played the part of a dutiful wife, was a cruel, promiscuous and evil woman who taunted him on the night he shot her with the news she was carrying another man’s child.
Whilst terrified by the implications of this revelation, Mrs de Winter is deeply relieved to discover that her husband hated his first wife and actually loves her. The couple pledge to work together to cover up the truth, and when an inquest into Rebecca's death returns a verdict of suicide, Maxim de Winter seems to be in the clear. However, Jack Favell, a cousin of Rebecca’s with whom she was having an affair, arrives at Manderley with a note which he claims will prove his relationship with Rebecca and undermine the evidence given by Mr de Winter at the inquest; he also threatens blackmail.
Maxim de Winter summons a local magistrate to hear Flavell's account. The magistrate dismisses Flavell's allegations, pointing out that he has no proof. Flavell attempts to produce evidence, and calls a local man as a witness, but he is once again unsuccessful. In the course of the ensuing discussions, which Mrs Danvers is invited to join, it emerges that Rebecca had seen a Doctor Baker in London shortly before her death, although no-one knows why. It is decided, therefore, that Mr and Mrs de Winter, the magistrate and Flavell will travel to London to interview the doctor. On arrival, they make the shocking discovery that Rebecca was, in fact, suffering from cancer at the time of her murder, and would only have had a few months to live; they also learn that she was unable to become pregnant.
With this new information to support the verdict of suicide, Mrs de Winter is convinced that they can now move forward with their lives, but Maxim de Winter maintains a sense of foreboding. A phone call to Manderley reveals that Mrs Danvers has left the house in a peculiar hurry. The couple set off home and, as they approach Manderley, see that the sky is tinged red. Ashes carried on the wind suggest that the house is on fire. We are left with some understanding of what may lie behind the couple’s exile abroad.