In London in 1864, Emily ‘Fido’ Faithfull is busy running a feminist printing press, and trying to improve the lot of the women of her age. Their injustices are brought forcefully home when she runs into an old friend, Helen Codrington. Helen’s marriage to an army officer is at breaking point, yet she is tied to him for life, and unable to marry Colonel Anderson, another officer who is madly in love with her. Fido offers Helen sympathy and friendship – but to her horror, quickly discovers she has unwittingly become an accomplice in Helen and Anderson’s affair.

The resultant divorce case – based on a real-life one – exposes the sordid but fascinating world of private detection brought into being by the 1857 Matrimonial Causes Act, which allowed men to divorce their wives for adultery, provided they could obtain proof that would satisfy a jury. And like the Victorian sensation novels of Dickens, Wilkie Collins and Mary Braddon for which Fido has a predilection, it’s an unputdownable read, with one outrageous twist after the next.