IN 1858, THE WRITER Charles Dickens sent to several London newspapers and magazines a note outlining the sorry state of his marriage. The announcement, a precursor to the boilerplate “please respect our privacy during this difficult time” appearing in modern tabloids when any celebrity relationship dissolves, alludes to Dickens’s separation from his wife, Catherine. His preemptive strike against the rumor mill, however, refuses to acknowledge reports of Dickens’s trysts with a stage actress some thirty years his junior:

Some domestic trouble of mine, of long-standing, on which I will make no further remark than that it claims to be respected, as being of a sacredly private nature, has lately been brought to an arrangement, which involves no anger or ill-will of any kind, and the whole origin, progress, and surrounding circumstances of which have been, throughout, within the knowledge of my children. It is amicably composed, and its details have now to be forgotten by those concerned in it.

Dickens and his wife would stay legally married until the former's death in 1870. Modern retellings of the affair attempt to explain away the not-fully-realized separation by saying that divorce was not an option in 1858; this is untrue. In that year Great Britain established the first divorce court, a place where the dissolution of marriage could be decided by judges instead of by the previously required Act of Parliament. The court granted more than 100 divorces in its first year — more than 10 times that of the previous annum.

One of those 1858 divorce cases, Robinson v. Robinson and Lane, involving a middle-class housewife, her domineering husband, and a handsome young doctor, is the subject of Kate Summerscale's new book, Mrs. Robinson's Disgrace: The Private Diary of a Victorian Lady. The Robinson divorce made headlines in city and local papers across the British Isles, and drew commentary from tangentially related figures like Charles Darwin and the aforementioned Mr. Dickens, but Summerscale's yarn centers on the titular Mrs. Robinson and her diaries. Her alleged infidelity was discovered by her husband, who found the unlocked diary while she lay in bed with a fever, and excerpts of her private writings were read aloud during the trial, exposing the innermost workings of her fantasy life and altering perception (contemporary and modern) of what a Victorian woman thought, felt, and created.

The union of Isabella and Henry Robinson was not a love match. Ten years his junior and the widowed mother to a toddler son, she was swept into the marriage largely out of financial need. She bore him two children; he had others from a previous marriage and would go on to have at least two more with mistresses. She wrote in her diary that he was “cold” and “uninterested in anything but business,” so when the family moved to Edinburgh in 1850, she worked hard to ingratiate herself to a circle of bright, middle- and professional-class men and women that included lawyers, novelists, and doctors — specifically a doctor, Edward Lane, and his wife, mother-in-law, and children. In Robinson’s diary (acquired by Summerscale via the National Archives), she makes her affections for Lane clear — even while cultivating a friendship with the rest of his family, she takes pleasure in his attentions, which are, in her early writings, ambiguous. Summerscale, however, interprets Robinso...