Incorrectly signing her name in the marriage registry leads Valeria Woodville to discover further disturbing information about her husband, Eustace Macallan. Each revelation leads to further questions as Valeria's journey prompts her to defy him, taking the law into her own hands as she endeavours to navigate her way through a series of false clues and obstructions.

Published in 1875, The Law and the Lady is one of Collins's later novels and is a remarkable early illustration of a female investigator as a main character. In the course of its narrative it questions Victorian society's perspectives of both law and lady.