Honoria Barbay, a genteel young woman, lives with her sister. She is in love with Captain Hawdon and is persuaded to elope with him, hoping that his father, who disapproves, will soften towards them. But the father cuts off his son completely and Hawdon is arrested for debt. He fakes suicide and disappears, leaving the pregnant Honoria believing he is dead.

She accepts the hand of Sir Leicester Dedlock, marrying after she has secretly given birth to a baby girl. Her sister tells her the baby is dead. Eighteen years later, as the respectable but cold Lady Dedlock, she chances upon handwriting she recognises in a legal document and asks Tulkinghorn, her husband's lawyer, to investigate. He, having developed a hatred for Lady Dedlock, senses that she holds a secret to do with the writer of the document. His suspicion sets in train a series of events involving Mr Guppy, at the firm of solicitors who commissioned the copying work; Nemo, the destitute copyist; his friend, 'Poor Jo', the crossing sweeper; Esther Summerson, the ward of Mr Jarndyce of Bleak House; and George, Captain Hawdon's man.

The death of Nemo (actually Hawdon) and the persecution of Lady Dedlock by Tulkinghorn leads to the lawyer's murder, and Inspector Bucket of the Police is brought in to find his killer. A manhunt ensues, and Lady Dedlock flees, believing she is suspected and having visited Esther, who she now knows to be her own daughter. She changes clothes with a countrywoman and evades capture. Pursued by Bucket and Esther, who now know her to be innocent, she doubles back to London, where she dies at the gates of the miserable cemetery where her former lover Nemo/Hawdon was buried in a pauper's grave.